The material selection platform
Coatings Ingredients
The material selection platform
Coatings Ingredients
Pigments for Paints and Coatings

Selecting Pigments for Paints, Coatings and Inks

Pigments are important constituents in paints, coatings, and inks. They impart color, bulk, and desired physical and chemical properties to the wet or dry film. There are plenty of pigments available in the market. Hence, it becomes difficult for the formulator to make the right selection.

Are you using the right approach to find the pigment of your choice? Get detailed knowledge about:

  • various pigment families used in inks, paints, and coatings
  • the properties to consider while choosing pigments
  • selecting the ideal product satisfying your formulation requirements

After reading this guide, resume your pigment selection here »


Are color pigments and dyes different?

Are color pigments and dyes different?

Pigments are finely ground natural or synthetic particles. They are practically insoluble in the medium in which they are dispersed. They are distinct particles, which gives the medium its color and opacity.

Pigments are organic or inorganic, colored, white, or black materials. They impart color when added to paints and coatings formulations. They also add bulk or desired physical and chemical properties to the wet or dry film.

The smallest units refer to primary particles. The particles' structure and shape depend on the crystallinity of the pigment. During the pigment production process, primary particles generally aggregate and generate agglomerates.

Pigment Dispersion
Pigments Dispersion

During the pigment dispersion into the polymer, high shear breaks up these agglomerates. This improves the tinting strength of the paints. Pigments are thus required to resist dissolving in solvents that they may contact during application. Otherwise, problems such as bleeding and migration may occur. Pigments are resistant to light, weathering, heat, and chemicals such as acids & alkalis. This depends on the demands of the particular application.

Dye is a substance that imparts color with some degree of permanence. Polymer Soluble Dyes are soluble in the medium in which they are dispersed. This means that there are no visible particles. Hence, the transparency of the medium remains unchanged.

Dispersion of dyes
Dyes Dispersion

Pigment dispersion - The step-by-step process

High-quality coatings of high brilliance and color strength are characterized by:

  • A perfect pigment dispersion
  • Optimal pigment particle size
  • Long-term stabilization of the dispersed particle in the formulation

Most organic pigments show better transparency as dispersion improves. In larger particle-size inorganic pigments, opacity is improved by good dispersion.

The dispersion process refers to the permanent breaking of agglomerates into primary particles. There are four aspects to the dispersion process:

  1. Deagglomeration – The breaking down of the agglomerates & aggregates by applying force. A mixture of both crushing and mechanical shearing force is applied here.

  2. Wetting – It occurs at the surface of a pigment when a surface-active agent sticks to the pigment's surface. It acts as a connection between the pigment and the binder. Wetting out time depends on the viscosity. Heat produced by the mechanical shearing process increases the temperature of the mixture. This thus reduces the viscosity, helping the wetting out process.

  3. Distribution – It demands the pigment to be equally dispersed throughout the binder system. A lower viscosity tends to lead to a more even pigment distribution.

  4. Stabilization – It prevents the pigments from re-agglomerating. The pigment dispersion is stabilized by dispersing agents to prevent the formation of uncontrolled flocculates. The resultant suspension is stabilized due to the adsorption of binder species or molecules at the pigment surface.

Want to know the science behind pigment dispersion? Discover more about the dispersion process.

Which are the common types of pigments?

Which are the common types of pigments?

Each pigment types have distinct properties that distinguish them from one another. Some main pigment classes include:

  • Organic pigments
  • Inorganic pigments
  • Functional pigments
  • Special effect pigments

Organic pigments do not disperse easily and form agglomerates (clumps of pigment particles). While inorganic pigments get more easily dispersed in the resin. Functional pigments impart a desired property to the coating. They create optical effects like metallic, hammer finish, and diverse color perceptions depending on the angle. Examples of functional pigments include corrosion inhibitors and special effect pigments.

Browse the largest online catalogue to select your pigment grades

Organic pigments Inorganic pigments 

Also search directly for:

Organic vs. inorganic pigments - Property comparison

Pigment Properties Inorganic Pigments Organic Pigments
Classical High-performance
Color, Purity Often dull Usually bright
Opacity High More or less transparent
Color strength Medium to Low Normally High
Light Fastness (Blue scale) Good to High (7-8) Low to Middle (< 7) Good to High (7-8)
Weather Resistance Varies (depending on chemistry) Insufficient Middle to High
Heat resistance
In general > 500°C
Rarely < 200°C
150 to 220°C 200 to 300°C
Fastness to solvents - Bleed resistance High Middle to Good Good to High
Resistance to chemicals Varies (depending on chemistry) High (except for salts) High
Price Low to Medium Medium High
Commercial Products Inorganic pigment grades Organic pigment grades

Now when the basic distinction is clear, find out in detail about these 2 types of pigments and see which one matches the best with your final application needs.

What are organic pigments?

What are organic pigments?

Organic Pigments for Inks and Coatings Organic pigments are traditionally transparent. Modern manufacturing techniques impart properties that are not associated with the chemical type. It is now possible to produce high-opacity organic pigments.

Organic pigments are relatively new. Natural dyes have been precipitated onto inorganic bases (known as lakes). They are used in artists' colors since the Middle Ages (e.g., madder lake and crimson lake). However, true organic pigments have been known since the early years of the 20th century. They divide into two sub-groups:

  1. One of vegetable origin, and
  2. Other of animal origin

Most organic pigments show better transparency as dispersion improves. While in the case of larger particle size inorganic pigments, opacity is improved by good dispersion.

Explore the range of organic pigments in detail below. Click on the specific pigment for your formulation:

 Organic Red Pigments

There are a lot of red pigments. To select the best pigment for your application, you need to know all the products available in this color and their properties.

Pigment Red 3, 4 & Pigment Orange 5
  • Moderate heat stability  
  • Limited solvent resistance
  • Good chemical resistance and light fastness
Relatively cheap pigments
BON arylamides
Pigment Red 2, 5, 12, 23, 112, 146, 170 & Pigment Orange 38
  • Good chemical stability
  • Limited light fastness and solvent resistance
Toner pigments
Pigment Red 48, 57, 60, 68
  • Excellent heat stability
  • Good solvent resistance
  • Poor alkali and acid resistance
Pigment Red 171, 175, 176, 185, 208
Pigment Violet 32 & Pigment Brown 25
  • High solvent resistance and good heat stability
Relatively economic when compared with other high-quality pigments.
Disazo condensation
Pigment Red 144, 166, 214, 220, 221, 242
Pigment Orange 31 & Pigment Brown 23
  • Excellent heat stability
  • Good solvent resistance
Pigment Red 122, 192, 202, 207, 209 & Pigment Violet 19
  • Excellent solvent resistance, chemical stability and heat stability
  • High light fastness and bright color
Relatively expensive
Pigment Red 123, 149, 178, 179, 190, 224
Pigment Violet 29 & Pigment Black 31, 32
  • Good chemical stability
  • Excellent light fastness, heat stability and solvent resistance
Expensive, because of their good properties
Pigment Red 177
  • Good heat stability and solvent resistance
  • Moderate-good light fastness
  • Bright and strong color
Pigment Red 168
  • Excellent light fastness and solvent resistance
  • Moderate-good Heat Stability
Pigment Red 216, 226 & Pigment Orange 51
  • Good solvent resistance
  • Low-moderate light fastness and gives a dull shade
Diketopyrrolo-pyrrole pigments (DPP)
Pigment Red 254, 255, 264, 270, 272 & Pigment Orange 71, 73
  • Excellent heat stability solvent resistance and weatherability
  • Good opacity and bright color
Often used in combination with other more economic pigments

 Organic Blue Pigments

The blue pigment range is dominated by one chemical type - Phthalocyanine. It is considered as the ideal pigment to impart blue color in paints and coatings.

Copper phthalocyanine Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16
  • Excellent solvent resistance and heat stability
  • High color strength
  • Very good light fastness & weatherability
  • Being one of the cheapest organic pigments on the market they provide very high tinctorial strength
These pigments are relatively transparent and can be used in solid, reduced, and metallic automotive coatings
Indanthrone Pigment Blue 60
  • Excellent chemical stability
  • Excellent solvent resistance, light fastness and weatherability
  • Good flocculation & heat stability
Used in high-performance paints, i.e. automotive OEM finishes, principally in metallic and pale shades

 Organic Green Pigments

The green spectrum is dominated by copper phthalocyanine pigments. The common method to reach green is by mixing yellows and blues, the desired brightness and economics being the two main factors determining the best approach.

Inorganic pigments play a comparatively insignificant role.

Phthalocyanine green Pigment Green 7, 36
  • Excellent solvent resistance, chemical stability, light fastness & weatherability
  • Good heat stability & tinctorial strength

 Organic Violet Pigments

Violet paints are not commonly used whereas violet pigments are. They are used to add blue tones to red paints, and red tones to blue paints, without affecting the intensity of the color.

Violet pigments can also be used to turn the yellow tint of titanium dioxide into white. Dioxazine violet is the most used violet pigment in the paint industry.

Dioxazine violet Pigment Violet 23, 37 Excellent heat stability and solvent resistance
Good light fastness
  • Possess a very small particle size which makes them vulnerable to flocculation
  • Can also produce plate out in some powder coating systems

Dioxazine violet pigments are used in a variety of paint systems:

In metallic paints, Pigment Violet 23 is more used because of its transparency and bluer shade.

 Organic Orange Pigments

Yellow and Orange pigments can often be difficult to differentiate. Numerous orange pigments can be produced via similar chemistry to inorganic yellow chrome pigments, and arylamide, isoindoline, and isoindoline yellow organic pigments.

Others tend to possess chemistry which is associated with red pigments, ie.

  • Cadmium reds and molybdate
  • Beta-naphthol and BON arylamide pigments

However, the pigments listed below are orange pigments in their own right:

Pyrazolone orange Pigment Orange 13, 34
  • Good solvent resistance and heat stability
  • Low light fastness
  • Bright
  • High tinctorial strength
Mainly used in printing inks.

Pigment Orange 34 can also be used in industrial finishes, especially when produced in its opaque form
Perinone orange Pigment Orange 43
  • Excellent solvent resistance, high heat stability and tinctorial strength
  • Good light fastness
  • Bright shade
  • Expensive to manufacture
Used in tinting systems

Organic Black Pigments

Black pigments are characterized by their origin:

  • Organic blacks
  • Inorganic blacks: iron oxides, graphite
  • Vegetable blacks: peach, charcoal, vine
  • Animal blacks: bones, ivory

Organic or inorganic blacks are the most important groups, as well as carbon black which are the most common black pigment.

Carbon Black Pigment
Black 6, 7, 8
  • Excellent light fastness, chemical and heat stability
  • Good resistance to solvents
  • Limitations include absorption, flocculation, dispersion and viscosity of the paint
  • The rubber industry is the biggest user of carbon blacks by a large margin. In comparison, the paint industry is only a modest user
  • The printing inks industry uses significant quantities
  • Z`Finer particle blacks are used for high-quality finishes such as in automotive paints on account of their higher jetness
  • Medium size blacks are used for intermediate quality paints
  • Coarser pigments are used for decorative paintsa nand tinting purposes
Graphite Pigment
Black 10
  • A soft pigment consisting of inert plate-like particles
  • These lamellar plates form layers in a paint film, which prevents water from penetrating
  • Good reinforcer of other pigments in anti-corrosive paints
  • Confers high spreading rates owing to the slippery nature of the particles
  • Limitation - It has low tinctorial strength and low color intensity
Aniline Black
Black 1
  • Oldest synthetic organic pigment discovered around 1860
  • Has a strong tinting strength and light absorption capability
  • Fastness properties are quite good
  • Low scattering power
  • Produces matt effects (velvety appearance) in paint because of its high binder demand
  • Mostly used in some speciality coatings where very deep blacks are required
  • However, its chromium content limits its application where physiological properties have to be considered
Anthraquinone Black Pigment
Black 20
  • Moderately good light fastness
  • Moderate solvent resistance
  • Used in camouflage paints, as its infrared spectra satisfies various standards

 Organic Brown Pigments

Iron oxide is the most important brown pigment, but a few organic pigments are used for specialty applications.

Benzimidazolone Pigment Red 171, 175, 176, 185, 208

Pigment Violet 32

Pigment Brown 25
  • High solvent resistance and good heat stability
  • Excellent Light fastness & weatherability
  • Mainly used in plastics
  • Also used in metallic automotive and vehicle refinishing paints
Disazo condensation Pigment Red 144, 166, 214, 220, 221, 242

Pigment Orange 31

Pigment Brown 23
  • Possess two azo red molecules linked to a diamine by means of carbonamide groups
  • Excellent heat stability and good solvent resistance
  • Color is often bright and ranges from scarlet through bluish red to violet and brown
  • Used in industrial and vehicle refinishing paints and as the basis of tinting systems

 Organic Yellow Pigments

A large number of organic yellow pigments are available. They differ by their:

  • Brightness of shade Opacity
  • Fastness requirements
  • Physiological properties, and
  • Economic considerations

These properties influence the choice of the pigments depending on the end application. As well as being used in yellow paints, yellow pigments are also used in oranges, greens and browns.

Arylamide Pigment Yellow 1, 3, 65, 73, 74, 75, 97, 111
  • Excellent light fastness and weatherability
  • Moderate tinctorial strength
  • Poor heat stability and solvent resistance
  • Applications limited to water-based and white spirit-based decorative paints
Diarylide CI Pigment Yellow 12,13,14,17,81,83...
  • Good resistance to heat, chemicals and solvents
  • High color strength but poor light fastness
  • Have limited use in paints but are used in the printing ink industry, where they are the basis of the yellow process ink
Benzimidazolone Pigment Yellow 120,151,154,175,181,194

Pigment Orange 36,60,62
  • Excellent light fastness and weatherability
  • Good chemical and solvent resistance and heat stability
  • More expensive than other monoazo pigments
Disazo condensation pigments Pigment Yellow 93, 94, 95, 128, 166
  • Excellent heat stability, chemical and solvent resistance
  • Relatively difficult to manufacture and reasonably expensive
Organic metal complexes Pigment Yellow 129, 153

Pigment Orange 65, 68
  • Have a good solvent resistance due to the introduction of a metal group into the molecule
Isoindolinone Pigment Yellow 109, 110, 173 & Pigment Orange 61
  • Moderate tinctorial strength
  • Good light fastness
  • Excellent solvent resistance, heat and chemical stability
Isoindoline Pigment Yellow 139, 185 & Pigment Orange 69
  • These pigments have good fastness properties and tinctorial strength
  • Do not resist to alkalis
Quinophthalone Pigment Yellow 138
  • Good heat stability and solvent resistance
  • Excellent light fastness
Anthrapyrimidine Pigment Yellow 108
  • Moderately good solvent resistance
  • Light fastness is not ideal as this pigment darkens when exposed to light
  • Expensive due to its complex nature
Flavanthrone Pigment Yellow 24
  • Reddish yellow color and transparent
  • Stronger than anthrapyrimidine
  • Light fastness is excellent for bright shades
  • Durable and has good heat stability

What are inorganic pigments?

What are inorganic pigments?

Inorganic Pigments for Inks and Coatings The use of inorganic pigments dates back to the early cave paintings that are 30,000 years old. Although they occur naturally, for the manufacturing of paint they usually require modification. All white pigments are inorganic and a wide range of colored pigments is also available.

Enlighten your knowledge in colored pigments given in detail below or simply click the specific pigment of your choice:

 Inorganic Red Pigments

The popular red inorganic pigments chemistries suitable for paints, coatings and inks are discussed below.

Lead chromate Pigment Red 103
CI 77601
  • Good opacity
  • Excellent Light fastness & weatherability
  • Low acids resistance
  • Excellent bases resistance
These pigments are relatively cheap
Lead Molybdate
Pigment Red 104
CI 77605
  • Good opacity durability and heat stability
  • Moderate alkali resistance
  • Excellent solvent resistance
Cadmium red
Pigment Red 108
CI 77202
  • Moderate tinctorial strength
  • Good light fastness
  • Bright color  Excellent  opacity and solvent resistance
  • Bad acid stability
Relatively expensive
Red iron oxide
Pigment Red 101 (synthetic) & Pigment Red 102 (natural)
  • Excellent heat stability, solvent resistance and chemical stability
  • Low tinctorial strength
Economical to use

 Inorganic Blue Pigments

The blue inorganic pigment range is dominated by one chemical type - Phthalocyanine. It is considered as the ideal pigment to impart blue color in paints and coatings.

Other blue pigments include:

  1. Indanthrone which is used for particular high quality applications
  2. Ultramarine and Prussian blue are two inorganic pigments occasionally used

The printing ink industry uses some cationic toners (phospho tungsto molybdic acid, ferrocyanide and alkali blue pigments), but their poor solvent and chemical resistance coupled with poor light fastness means they have virtually no use in paint.

Prussian blue Pigment Blue 27
CI 77510 / 77520
  • Excellent solvent resistance and good heat stability
  • Excellent light fastness, poor alkali stability. It gives an intense, strong color
  • Because of its hygroscopic nature (approx. 4% of water), Prussian blue is difficult to wet
  • This pigment is flammable. On burning, it produces HCN, NH3, CO, and CO2 gases
This pigment is mainly used in printing inks. It can also be used in industrial coatings and in automotive paints
Pigment Blue 29
CI 77007
  • Excellent solvent resistance and heat stability
  • Good alkali stability and light fastness
  • Poor stability to acids
Cobalt blue Pigment Blue 28
CI 77346
Pigment Blue 36 & Pigment Green 50
  • Excellent chemical and heat stability
  • Good solvent resistance
Used in powder coatings, silicone paints and inks

 Inorganic Green Pigments

The green inorganic pigments spectrum is dominated by copper phthalocyanine pigments. The common method to reach green is by mixing yellows and blues, the desired brightness and economics being the two main factors determining the best approach. Inorganic pigments play a comparatively insignificant role.

Chrome green Pigment Green 15 Obtained by co-precipitation or dry blending of Chrome Yellow and Prussian Blue
  • These pigments have the same properties as the pigments used for their preparation
  • They have a tendency to float or flood because they wet out at different rates
Chromium oxide green Pigment Green 17
CI 77288
  • Excellent solvent resistance, heat- & chemical stability, light fastness & weatherability
  • Good opacity
  • Low tinctorial strength
Hydrated chromium oxide Pigment Green 18
CI 77289
Cr2O(OH)4 - Similar in chemistry to chromium oxide
  • Excellent alkalis resistance, light fastness & weatherability
  • Low acids resistance & heat stability

Inorganic Black Pigments

Black inorganic pigments are characterized by their origin:

  • Organic blacks
  • Inorganic blacks: iron oxides, graphite
  • Vegetable blacks: peach, charcoal, vine
  • Animal blacks: bones, ivory

Organic or inorganic blacks are the most important groups, as well as carbon black which are the most common black pigment.

Black Iron Oxide Pigment
Black 11
  • Relatively cheap and inert pigment
  • Excellent solvent- & chemical resistance and light fastness
  • Excellent durability and weatherability
  • Low tinctorial strength — An advantage when used as a tinter, as it allows more control
  • Low oil absorption as compared to other black pigments
  • Mainly used in applications where the tendency of carbon black to float cannot be tolerated (for example in grey tones in combination with titanium dioxide)
Black Micaceous Iron Oxide Not listed
  • Inert
  • Greyish appearance and a shiny surface
  • Capacity to absorb UV radiation also protects the polymers when used as binders
  • Plate-like structure prevents the passage of oxygen and moisture
  • Should not be over-dispersed because the platelets can be damaged and rendered ineffective
  • Used in heavy-duty coatings to protect structural steelwork

 Brown Pigments

Iron oxide is the most important brown inorganic pigment, but a few organic pigments are used for specialty applications.

Iron Oxide Brown Pigment Brown
6, 7
  • The natural form of Brown Iron Oxide is called burnt sienna or burnt umber
  • Pigments are made from naturally occurring ores that are then heated, various shades depend on the impurities, especially MnO content
  • Has low tinting strength but is not opaque
  • Imparts a rich brown color and give excellent fastness properties
  • Synthetic brown iron oxides are not used in paint formulations, as similar shades can be obtained using mixtures of cheaper pigments
  • Burnt sienna and burnt umber have become well known due to their use for artists' colors. But they can be used in commercial paints
Metal complex brown Pigment
Brown 33
  • It has a spinel structure
  • Excellent light fastness and high heat stability
  • Mainly used in ceramics
  • Can be used in coil coatings, where its high heat stability and excellent fastness properties make it a useful pigment

White Pigments for Coatings and Inks

All white pigments are inorganic. The more used white pigment is Titanium Dioxide.

Titanium Dioxide became the dominant white pigment after the Second World War. White pigments are compared by their reducing power. This corresponds to the amount of white pigment needed to produce an equal depth of shade when used with a standard amount of colored pigment.

Related Read: Titanium Dioxide Pigment for Paints & Coatings - Complete Guide

Titanium Dioxide Pigment White 6
CI 77891
  • Exists in three crystal forms: Brookite - Not used as a pigment; Anatase - Used occasionally; Rutile - The most commonly used crystal form
  • High resistance to most chemicals, organic solvents and hea
  • High refractive index
  • Good durability and resistance to industrial atmospheres
  • But, photoreactivity reduces the light fastness of some colored pigments and nearly all organic pigments
  • Has favorable physiological properties due to its inert composition
  • Suitable for use in food packaging, toys, and other sensitive applications, provided that it meets purity criteria
  • Can be used in all building and industry coating formulations
White Lead Pigment White 1
  • Formula: 2PbCO3Pb(OH)2
  • Reacts with acidic binders to provide tough and durable elastic films
  • Reacts with sulphurous gases in industrial atmospheres and turns black
  • Use of white lead is severely restricted due to concerns regarding the toxicity of lead compounds
Zinc Oxide Pigment White 4
CI 77947
  • An amphoteric oxide
  • Good white color when it has a high purity (> 99.5%)
  • Hexagonal crystal structure has empty spaces due to the big difference in size between zinc and oxygen atoms resulting in semi-conductor properties
  • In a binder with a low acid index, it produces zinc soaps which improve the wet out of the pigment and make the dispersion easier
  • In a binder with a high acid index, it can cause severe thickening
  • Improves the viscosity of the paint and reduces the sedimentation
  • Excellent bases resistance
  • Can be used as additional pigment with TiO2 to improve chalking resistance, or with lithopone
  • Not very interesting as a white pigment, but it can be used as UV absorber, curing agent or fungicide
Zinc Sulphide Pigment White 7
CI 77975
  • Formula: ZnS, nH2O where n=0 or 1. It can contain traces of copper. ZnO crystallizes in a hexagonal system.
  • Produces a good, strong white color, good opacity and a high degree of chemical inertness
  • It chalks badly
  • Not used very commonly. It can be used in association with other white pigments in coil coatings
Lithopone Pigment White 5
CI 77115
  • Co-precipitate of BaSO4 and ZnS. The mix of the two forms does not separate in the coating
  • Excellent Light fastness & weatherability
  • Can be degraded under UV light and lead to a grayer color.To avoid this degradation, it is possible to add nicker or iron during the preparation of lithopone, before calcination cobalt or copper
  • Can be used in every type of coating
Antimony Oxide Pigment White 11
CI 77052
  • Formula: Sb2O3, It is inert and moderately opaque
  • Originally used to reduce the chalking of anatase titanium dioxide
  • Has excellent light fastness and high heat stability
  • Mainly used in fire-retardant paints, because its heavy gas can choke flames

 Yellow Pigments for Coatings and Inks

A large number of inorganic yellow pigments are available. They differ by their:

  • Brightness of shade
  • Opacity
  • Fastness requirements
  • Physiological properties, and
  • Economic considerations

These properties influence the choice of the pigments depending on the end application. As well as being used in yellow paints, yellow pigments are also used in oranges, greens and browns.

Lead chromate Pigment Yellow 34
CI 77600
CI 77603
  • Yellow Lead Chromates have very bright shades and high chroma, making them ideal for full shade yellow paints
  • Excellent opacity and solvent resistance
  • Fading can occur because they are sensitive to alkalis and acids
  • Their light fastness is usually satisfactory in full shade, but they darken on exposure to light
  • Contains both lead and chromium (VI) which effectively limits their application to certain industrial finishes
  • Warning labels are required on European paints using these pigments
  • Disposal of waste can also be problematic and local regulations carefully followed
Cadmium yellow Pigment Yellow 37
CI 77199
  • Gives good quality light fastness in full shades, however, when exposed to industrial atmospheres it discolors and fades
  • Presents bright colors with high chroma
  • Offers excellent solvent and alkali resistance and high heat stability
  • Toxic in nature. Thus, in Europe, its use in nearly all coatings is prohibited for environmental reasons
Yellow oxides Pigment
Yellow 42 & 43
  • Excellent light fastness, durability, dispersibility
  • High resistance to chemicals and solvents
  • High refractive index and good hiding power
  • Limited heat stability - When exposed to temperatures higher than 105°C they begin to lose water, causing their shade to shift towards red. This color shift accelerates as the temperature or time of exposure increases
Bismuth vanadate Pigment Yellow 184
  • An intense, bright yellow pigment with a greenish shade
  • When combined with organic pigments, it generates very bright shades with high chroma and high covering power
  • Has high opacity, light fastness, excellent heat and solvent resistance and good hiding power
  • Can only be harmful at high concentrations. Low dusting grades minimize this risk

Inorganic Color Pigments by Shepherd

Extender Pigments for Coatings and Inks

  • Extender pigments are added in order to reduce the cost of a paint formulation. They are also used to modify the flow (viscosity), sedimentation stability and film strength.
  • Most extender pigments appear white and possess a refractive index similar to commonly used binders.
  • Most of the extender pigments occur naturally and others can be produced synthetically.
  • Aluminum silicate, magnesium silicate (talc), silica, calcium carbonate (synthetic and natural) and barium sulfate are some commonly used extender in paints and coatings.

Aluminum silicate (china clay) Pigment White 19
  • Formula: Al2O3, 2SiO2, 2H2O
  • Inert and has a good color
  • Excellent chemical stability and light fastness
  • An inexpensive flatting agent that produces a structure that improves the suspension of other pigments
  • Imparts some thixotropy in paints
  • Mainly used in water-borne decorative paints
Magnesium silicate Pigment White 26
  • Formula: 3MgO.4SO2 H2O
  • Inert and hydrophobic
  • Does not settle in the wet paint because of its plate-like form
  • Provides some resistance to humidity, improves flow behavior, and enhances the sanding properties of paint films
  • Used in both water- and solvent-based decorative paints, in undercoats and industrial finishes, in coatings for building and construction, and in anti-corrosion paints
Silica Pigment White 27
  • Formula: SiO2
  • Fine particle size
  • Has excellent chemical stability
  • Used as a matting agent to reduce paints gloss
  • Improves intercoat adhesion and the sanding properties of the paint film
Calcium carbonate Pigment White 18
  • Formula: CaCO3
  • used in water- and solvent-based paints, for interior and exterior decoration, and in many other coatings
Barium sulphate Pigment White 21, 22
  • Formula: BaSO4
  • Very inert and insoluble
  • Natural barium sulphate is used in anti-corrosion paints, industrial paints and coatings for building and construction
  • Synthetic barium sulphate is used in primers, undercoats, and industrial finishes

Corrosion Inhibiting Pigments for Coatings & Inks

Corrosion is the destruction or degradation of metal by chemical attack. Corrosion inhibiting pigments can help prevent corrosion by:

  • Physically obstructing the passage of water and oxygen
  • Protecting the anodic sites that have become pitted
  • Providing soluble pacifying ions to protect the metal
  • Producing an insoluble film to prevent active corrosion

Most of these pigments can be toxic because of lead or chrome VI they contain. Corrosion inhibiting pigments have to be selected carefully depending on the application.

Red lead Pigment Red 105
  • Formula: Pb3O4
  • Reacts with the acidic groups in the resin to produce lead soaps that passivate iron and steel surfaces
  • Mainly used in primers for metal protection
Basic lead silicochromate  
  • Formula: PbSiO3 3PbO PbCrO4 PbO3
  • Easily dispersible
  • Imparts a high-quality metal protection in automotive paints and structural steel
  • Finer grades find use in electrocoat paints
Zinc chromate Pigment Yellow 36
  • Formula: ZnCrO4
  • Liberates chromate ions, which passivate metal surfaces, producing a protective film at the anodes that prevents the anodic reaction
  • In the past they have been used for iron, steel and aluminum protection, however their physiological properties make them unsuitable
Calcium, strontium and zinc molybdate  
  • Formula:CaMoO4, SrMoO4, ZnMoO4
  • These three pigments passivate the anode
  • Their use has grown considerably in recent years on account of their more favorable physiological properties
Calcium plumbate Pigment Brown 10
  • Formula:Ca2PbO4
  • A powerful oxidizing agent which also reacts with the acid groups in binders and fatty acid groups such as linseed oil to produce lead and calcium soaps
  • Its corrosion-inhibiting effect is a result of the pigments capacity to oxidize soluble iron compounds formed in anodic areas, which then form an insoluble film of iron compounds at the anode. This neutralizes that element of the corrosion cell and restricts any further corrosion
  • Promotes adhesion in the paint film and confers toughness
Zinc phosphate Pigment White 32
  • Formula: Zn3(PO4)2 2H2O
  • Offers good durability, excellent intercoat adhesion and good flow properties in paint systems
  • In industrial atmospheres, it reacts with ammonium sulphate to form complex hetero acids, which inhibit corrosion
Zinc dust Pigment Metal 6 & Pigment Black 16
  • Formula: Zn
  • Fine bluish grey powder that reacts with alkalis to produce zincates and with oils to make zinc soaps
  • Corrosion resistance is generated via a sacrificial chemical reaction of the pigment rather than the steel substrate
  • protects film formers in exterior coatings by absorbing UV radiation

How to measure the performance of pigments?

How to measure the performance of pigments?

Color of pigment

The color of a pigment is mainly dependent on its chemical structure. It is determined by the selective absorption and reflection of various wavelengths of light at the surface of the pigment.

Colored pigments absorb part of all the wavelengths of light. For example:

  • Blue pigment reflects the blue wavelengths of the incident white light and absorbs all of the other wavelengths. Hence, a blue car in orange sodium light looks black, because sodium light contains virtually no blue component.

  • Black pigments absorb almost all the light.

  • White pigments reflect virtually all the visible light falling on their surfaces.

  • Fluorescent pigments have an interesting characteristic. They have a high reflection in specific areas of the visible spectrum. They also absorb light in areas outside the visible spectrum (i.e., ultra-violets that the human eye cannot detect). They split the energy up, and re-emitting it in the visible spectrum.

Hence, they appear to emit more light than actually falls upon them, producing their brilliant color.

Color strength

Color strength (or tinctorial strength) must be considered when choosing a pigment. Color strength is the facility with which a colored pigment maintains its characteristic color when mixed with another pigment. The higher the color strength, the less pigment is required to achieve a standard depth of shade.

  1. Chemical Structure is one of the factors that influence the color strength of a pigment.

    • In organic pigments, color strength depends on the ability to absorb certain wavelengths of light. Highly conjugated molecules and highly aromatic ones show increased color strength.
    • Inorganic pigments that are colored due to having metals in two valency states, show high color strength. In contrast, those that have a cation trapped in a crystal lattice are weakly colored.

  2. Particle size also influences the color strength of a pigment. Higher color strength is obtained with smaller particles. Manufacturing conditions are the main factor to consider while formulating. They influence the particle size of pigment crystals. Pigment manufacturers play a crucial role. They can:

    • Reduce the size of the particles by preventing the growth of crystals during synthesis
    • Increase color strength by efficient dispersion

    Pigment dispersion also plays a major role in the color strength of the paint. It imparts colloidal stability to the finer particles. Thus avoiding their flocculation and using their full intrinsic color strength.

Get in touch with our expert consultant to troubleshoot poor pigment dispersion cases such as color strength, hiding power, paint stability, conductivity, and corrosion resistance.

Pigment dispersion & stabilization root causes

Heat resistance

Few pigments degrade at temperatures normally associated with coatings. However, at higher temperatures, pigments become more soluble and shading can occur. Thus, for organic pigments, heat stability is closely related to solvent resistance.

Some pigments prove to be satisfactory at a certain stoving temperature. These pigments may be totally inadequate to perform in an application requiring 10°C more. Chemical stability is also likely to be critical at elevated temperatures. This is typically the case in powder coating systems.

Another key area is coil coatings, as metal complex pigments may react with stabilizers at elevated temperatures. This can cause major shifts in shade. Modifications can occur in the crystal structure of pigments at elevated temperatures.

Pigments with high crystallinity are usually more heat resistant than polymorphic pigments. This is because different crystal modifications may respond differently to heat. Typically, inorganic pigments have enhanced heat stability. Yellow iron oxide is an exception. It loses water from the crystal at high temperatures.

Heat stability is system dependent, and this must be reflected in any test. All tests assess color at various temperature intervals. They evaluate the color difference between the sample and a standard, processed at the minimum temperature.

Light fastness

Light fastness is evaluated in relation to the whole pigmented system, not just the pigment. The binder imparts a varying degree of protection to the pigment. So, the same pigment will tend to have better light fastness in a polymer than it will in paint.

Pigments will nearly always have a much poorer light fastness in a printing ink system, where there is less resin to protect the pigment, and where there is a double effect of light passing through the pigmented layer, being reflected by the substrate and back through the pigmented layer.

Other pigments may influence light fastness in a pigmented system. These include:

  • Titanium dioxide promotes the photodegradation of most organic pigments. Therefore, high ratios of titanium dioxide led to poorer levels of light fastness.
  • Iron oxide can improve the light fastness of organic pigments. This is due to the fact that it is an effective absorber of UV light.

When the association of two pigments gives a better light fastness, it is called a synergistic effect. When the light fastness obtained is lower, it is called an antagonistic effect.

Some inorganic pigments are unchanged by exposure to light. But most pigments, and all organic pigments, are changed in some way: darkening or complete fading can occur.

A pigment's ability to resist light is influenced considerably by its chemical constitution. Other less significant influences are:

  • pigment concentration,
  • crystal modification, and
  • particle size distribution

Additionally, factors in the environment can dramatically affect results. These include the presence of water and chemicals in the atmosphere or in the paint system.

The light fastness of a pigmented system can be truly tested in the final formulation and application. Light fastness tests must be carried out only under carefully controlled test conditions.

Weather stability

For outdoor applications, coloring pigments should be selected for their weather resistance characteristics. This property is closely related to light fastness. Weatherability adds the extra dimension of atmospheric conditions (including salt from the sea, waste gases from industrial areas, or very low humidity from desert conditions). Weather-resistant pigments are usually light fast, but the reverse is not always the case.

The selection of pigments for outdoor use depends on:

  • Outdoor performance required (lifetime, climatic region/ Kilo Langley)
  • Binder type
  • Concentration of the pigment
  • Presence of titanium dioxide (which typically accelerates fading)
  • Concentration and type of light stabilizers used

Performance can also be influenced by the surface of the painted object and by the processing heat history.

The best way to assess weathering resistance in service is by using outdoor exposure tests in the climatic region(s) concerned. This is clearly not always feasible. The widely used alternative is accelerated testing. Machines are available which in addition to a xenon lamp; include wet cycles interspersed between longer dry cycles. Weatherability is designated in terms of the 1-5 Grey Scale. 5 represents no change and 1 a severe change.


A pigment must be insoluble in the vehicle (the medium in which it is dispersed). It must not react with any of the components of the paint, such as crosslinking agents.

Pigments should retain these properties even when the paint is being dried. The drying of paint is frequently carried out at elevated temperatures. In the dried film, the pigment must also remain unaffected by the substrate and agents with which it comes into contact including water. The water may simply be in the form of condensation, or acidic industrial atmospheres.

Organic pigments may dissolve to a limited extent in organic solvents. Whereas inorganic pigments may be affected by other components. Under certain conditions, pigments may dissolve, leading to application problems.

The solubility of a pigment generates the following problems:

  1. Blooming - If the pigment dissolves in the solvent, as the paint dries, the solvent comes to the surface and evaporates. It leaves crystals of pigment on the surface in the form of a fine powder. As solubility increases with temperature, this phenomenon worsens at elevated temperatures.

  2. Plate out - The effect of plate out looks similar to blooming but occurs in plastics and powder coatings. This effect is not due to the pigment dissolving. But because of the surface of the pigment that is not being properly wetted out. It usually occurs mainly with complex pigments and once wiped from the surface does not reappear.

  3. Bleeding - Pigments in a dried paint film may dissolve in the solvent contained in a new coat of paint applied on top of the original film. If the topcoat is a different color, particularly a white or pale color, the result can be disastrous. Again, elevated temperatures exacerbate the problem.

  4. Recrystallization - This phenomenon was almost unknown until the introduction of bead mills. During the milling stage, heat is generated, which dissolves a portion of the pigment. Over some time, the dissolved "pigment" starts to precipitate. It loses its brilliance and color strength. This becomes noticeable in paints containing two different colored pigments with different solubility. The more soluble pigment dissolves and then as it comes out of solution and precipitates, the paint will take the shade of the second pigment. Recrystallization can even take place in aqueous systems. It can be avoided by using less soluble pigments and/or by controlling the temperature during the dispersion process.

Opacity/Hiding power

Hiding power is the ability of a pigmented coating to obliterate the surface. It is dependent on the ability of the film to absorb and scatter light. Naturally, the thickness of the film and the concentration of the pigment play a fundamental role. The color is also important.

Hiding power of pigments
Hiding power

Dark, saturated colors, such as blacks and deep blues, absorb most light falling upon them, whereas yellows do not. However, carbon black and most organic blue pigments are fairly transparent. This is because they do not scatter the light that falls on them. In contrast, titanium dioxide absorbs almost no light. Yet its capacity to scatter light ensures that at a sufficiently high concentration, it will cover the substrate being coated. It is common practice to use a combination of pigments to achieve the best results.

A key factor in the opacity of a pigment is its refractive index (RI), which measures the ability of a substance to bend light. The opacifying effect is proportional to the difference between the refractive index of the pigment and that of the medium in which it is dispersed. This is one of the main reasons why titanium dioxide is now almost universally used as the white pigment in paint.

Medium RI
Air 1.0
Water 1.33
Film Formers 1.4-1.6
Pigment / Filler RI
Calcium carbonate 1.58
China clay (aluminium silicate) 1.56
Talc (magnesium silicate) 1.55
Barytes (barium sulphate) 1.64
Lithopone 30% (zinc sulphide/barium sulphate) 1.84
Zinc oxide 2.01
Zinc sulphide 2.37
Titanium dioxide: 
Solve all your problems related to poor pigment and filler dispersion.

Inorganic pigments have a high refractive index and organic pigments have much lower values. Consequently, most inorganic pigments are opaque, whereas organic pigments are transparent.

The particle size distribution of the pigment is another factor that plays an important role in opacity. As the particle size increases, the ability of the particle to scatter light increases, up to a maximum. It then starts to decrease. This ability to scatter light increases the hiding power of the pigment. Therefore the hiding power also reaches a maximum and then decreases as the particle size increases.

Effect of particle size on scattering
Effect of particle size on scattering

Whereas the refractive index of a compound cannot be altered, the pigment manufacturer can influence the particle size of pigments. Consequently, particle size selection has become one of the principal developments in pigment technology in recent years.

Measurement of opacity - The coating is applied in a wedge shape over a contrast chart. The film thickness is built up over the length of the chart, which is attached to a metal panel. The point at which complete obliteration is observed is noted and the film thickness at that point measured.


Usually, transparency is obtained by reducing pigment particle size as much as possible. This is achieved by surrounding the particles as soon as they are formed with a coating, which prevents the growth of crystals. The most common products used for this coating are rosin or rosin derivatives. This is particularly useful for printing ink pigments that are required to have high transparency. It has the added advantage that such pigments are more easily dispersed.

Iron oxide pigments can be opaque or transparent. The transparent variety is an important group of inorganic pigments. This is because they are widely used for metallic finishes where:

  • their high level of transparency gives an attractive finish, and
  • their weatherability resistance improves the weatherability of pigments with which they can be combined.

This is known as a synergistic effect. Transparent iron oxides depend on the particles being unusually small, and also having a crystal shape. The dispersion process can influence transparency. This is due to the breaking up agglomerates of particles into individual primary particles. However, primary particles are not split up by the dispersion process. All one can do is make full use of the pigment's original particle size. Good dispersion will maximize the transparency of a small particle.

Measuring Transparency - Assessed by applying the coating over a black-and-white contrast chart and measuring the color difference. The greater the color difference, the higher the transparency.

Chemical stability

Resin, crosslinking agents, UV initiators, and any other additives may react with the pigment and alter its performance. When UV-cured coatings were new to the market, some additives reduced their storage stability. This causes the coating to gel in the can. View all the available pigments for UV-cured coatings »

A great deal of care must be taken when selecting pigments for powder coatings. The initiator can change the pigment shade and reduce fastness properties. Reputable pigment manufacturers publish data on such systems and can offer assistance in case of difficulties.

Another adverse effect can come from:

  • Chemicals that the coating gets in contact with. Water, in the form of condensation, can seriously affect a paint film, particularly in bathrooms and kitchens. Many of the detergents used for cleaning paintwork are harsh. They have an abrasive effect on the pigment. It is essential that if the coating comes in contact with food, the coating is unaffected and the food remains unchanged.

  • Many testing processes concerning chemical stability consist of applying the chemical to the surface of the coating. This keeps them in contact for a given time, then measuring the discoloration of the coating and/or the staining of the chemical concerned.

Which properties to consider while selecting pigments?

Which properties to consider while selecting pigments?

Crystal structure

Pigments can be crystalline or non-crystalline (amorphous). In crystalline pigments, the atoms within each molecule are arranged in a well-structured pattern. However, in amorphous pigments, the atoms are randomly arranged. It is also possible for materials to have several different crystalline forms. This is known as polymorphism.

Color is dependent on these different structures. There exist pigments that have chemically identical entities in different crystal forms. Yet these polymorphic pigments are not suitable for use as a pigment. Examples of such polymorphic pigments include:

Techniques for influencing the desired crystal form and particle distribution are being developed. This is done by pigment manufacturers to optimize the commercial product for end applications.

Particle shape

Particle shape can influence the shade of a pigment and the properties of the paint. The following parameters determine the shape of particles:

  • chemical structure,
  • crystalline structure, or
  • synthesis of a pigment

The primary particles of a pigment may be nodular, spherical, prismatic, acicular, or lamellar. Primary particles are composed of single particles. The smaller these particles, the greater their surface energy. Thus, the more likely it is that they will clump together during manufacturing.

It is not practical to supply pigments in the form of primary particles as they would be more like smoke than powder. In practice, they only exist as the pigment is synthesized. When particles clump during the manufacturing process they form either aggregates or agglomerates.

  • Aggregates are connected along crystal boundaries during synthesis or drying. It is difficult to separate them. Hence, pigment manufacturers attempt to avoid their formation during the pigment's production.
  • Agglomerates are loose clusters of primary particles. They can break down via an efficient dispersion process. Following this process, it is still possible for particles to re-agglomerate into loosely held groups. These groups are known as flocculates. This commonly occurs when there is a rapid change of state, i.e.,
    • Too rapid dilution or
    • The addition of an incompatible substance

Flocculation results in a loss of tinctorial strength. However, flocculates are usually easier to separate than true agglomerates. Even normal shear such as brushing out is sufficient for their separation. This result in an uneven increase in tinctorial strength, depending on how much shear has been developing.

One point to note during brushing out is that small particles are more susceptible to flocculation than larger ones. So pigments at risk are carbon blacks and organic pigments such as phthalocyanine and dioxazine violet pigments. There are an increasing number of flocculation-stable grades being released in the market.

Practical Tips for Pigment Dispersion & Stabilization

Particle size

Pigment particles are not usually spherical. They can have different dimensions depending on whether one measures the length, width or height. Particle size is an average diameter of primary particles. Typical ranges are:

  • Carbon black - 0.01 to 0.08 µm;
  • Titanium dioxide - 0.22 to 0.24 µm;
  • Organics - 0.01 to 1.00 µm;
  • Inorganics - 0.10 to 5.00 µm;

Extender pigments can be among the coarsest pigment particles, up to 50 µm. But other types can be exceptionally fine (e.g., the precipitated silicas).

The pigment's particle size can affect its color, hide and settling characteristics. Large particles usually settle faster than smaller ones, and smaller ones are harder to disperse. Light scattering is also often influenced by pigment size. And the distribution will also affect the colloidal stability and color.

Surface area & oil absorption

The surface area is the total area of the solid surface. The unit of the surface area is square units (m2) and is usually defined as 1 gram of pigment. Typical values for organic pigments are between 10 and 130m2. This surface area is determined by an accepted measurement technique such as the BET (Brunauer, Emmett, and Teller) method using nitrogen adsorption. This technique consists in calculating the adsorption properties of the pigment.

The surface area is closely linked to the pigment's demand for binder. Larger particles have a smaller surface area and therefore a lower demand for binder. As the size of the particle of pigment is small, the surface area becomes large. As a result, the paint needs a large amount of binder to wet each pigment particle during the dispersion process.

Oil absorption is the amount of oil that is required to "wet out" 100 grams of pigment and to make paint. Oil Absorption is expressed in number of grams of oil per 100 grams of pigment (or volume relationship from weight).

Oil absorption = Number of grams of oil/100 grams of pigment

This value varies depending on the pigment's physical nature and particle size. The amount of oil affects the time of dryness. In general, the large amount of oil causes yellowing and delay of dryness.

Hardness of the pigments

Hardness is usually based on Mohs Hardness Scale. The hardness of the pigment is measured by comparison with the ten classes of the Mohs scale.

In the absolute scale of the hardness (of Rosiwal), the abrasion resistance is measured with proofs from laboratory, and by attributing to the corindone the value 1000.

Also for the Knoop scale, the values of hardness are absolute. They depend on the depth of the signs engraved on the minerals due to a special utensil with a diamond point, with which a standard of force is applied.

Mineral Mohs Scale Rosiwal Scale Knoop Scale
Gold 0 - -
Talc 1 0.03 1
Gypsum 2 1.25 32
Calcite 3 4.5 135
Fluorite 4 5 163
Apatite 5 6.5 430
Orthoclase 6 37 560
Quartz 7 120 820
Topaz 8 175 1340
Corundum 9 1000 1800
Diamond 10 140000 7000

These scales help define how hard a pigment is and if it will be easily abraded. The hardness of the pigment can affect the durability and abrasion resistance of the film. The hardness scales also allow the formulator to better define milling equipment needs and end-use. Some pigments are soft and can be damaged by milling, especially when placed in a ball mill for extended periods of time.

Another point to consider is the pigment's solubility and the effect of solvent on the pigment's hardness and structure.

Quantity of Pigment

The amount of pigment used in paint is determined by:

The paint technologist works on one of two main concepts:

  1. Pigment volume concentration (PVC) -
    • It fundamental concern when formulating paints with optimum durability. There is a critical point that represents the densest packing of the pigment particles. This aligns with the degree of dispersion of the system. For systems requiring high gloss, low PVC is required. Primers and undercoats can have much higher PVC - up to 90%.

  2. Pigment to binder ratio (P:B) -
    • The P:B ratio, by weight or occasionally by volume, is a much simpler calculation. It is often used to assist in formulating a good mill base and for balancing a formulation for gloss and opacity.

Binders used in formulations

The binder in the paint system plays a key role in terms of determining the pigment and the type of solvent in which it is dissolved.

  • A common choice for a solvent is water as it is compatible with most polymers, except some toners.
  • White spirit is a commonly used solvent for long oil alkyd paints. These are widely used in decorative gloss paints. A large majority of pigments are almost insoluble in white spirit. So it rarely narrows the choice of pigments.
  • Industrial finishes can be based on solvents such as xylene, ketones, and esters. They are very powerful and can dissolve pigments with poor or only moderate resistance to solvents.

It is also necessary to consider whether the coating will be overcoated. For example, in the case of a car getting repaired, the pigment used on the original finish will have to be fast to overcoating.

In powder coatings, crosslinking agents can affect the pigment. Hence, the pigments must be compatible with these agents at temperatures employed during application. It is therefore evident that the type of resin and solvent used remain key factors in the choice of pigment.

Paint performance in end application

An awareness of the end use of the paint is essential, as durability and chemical resistance requirements. The maximum price that can be tolerated for improved performance depends on this knowledge.

For example, a low-quality pigment would be insufficient in an automotive finish, just as a high-quality pigment would be unnecessary for use in a gardening tool.

Paints can be classified according to the market in which they are used, such as:

  • Building, architectural or decorative
  • Automotive finishes, OEM (original equipment manufacturers) or VR (vehicle refinishes), and
  • Industrial finishes

In the same way, pigments used in paint do not require the same properties as pigments used for ink applications.

Find suitable pigment grade for your product, analyze technical data of each product, get technical assistance or request samples.



Leave a comment

Want to comment?

No Account yet?

Rate this Content
8 Comments on "Pigments for Paints, Coatings and Inks"
Pratibha B Jun 2, 2024
Very informative who has to fine tune the product. Thought provoking and appealing experimentative problem solving
Aparna K Mar 30, 2023
Thank you very informative
farouk m Jun 25, 2022
great article
Thaer M Jun 7, 2020
very useful article for R&D Chemists
Riyanka D May 20, 2020
Really helpful article
Zohair O Apr 15, 2020
I have an inorganic rhodamine powder which solvent is suitable for it and thank you
Thaer M Oct 16, 2018
very useful article for R&D Chemists
David W Jun 15, 2018
Fantastic Overview of pigments, should be required reading for young (and old) chemists and technicians.

Back to Top