To protect and decorate. These properties of coatings are essential.
It is admitted for many paints that a perfect appearance means also a perfect leveling. Poor leveling (like orange peel or ghosting) may not influence significantly the paint parameters in time, as it is more aesthetic orientated. But the leveling agent itself may cause some severe issues.
A correct leveling agent helps in reaching the wanted leveling. But a wrong choice may lead to craters, pinholes, loss of gloss or even intercoat adhesion problems.
Leveling is strongly linked with the flow properties of the paint, and the surface tension will play an important role on the paint appearance.
This guide will focus on the paint leveling agents, and I invite you to read the Substrate Wetting Agent guide for a complete overview of the influence of the surface tension on the paint properties.
Leveling Agent: A Surface Tension Story!
Leveling is an important aesthetic parameter of the paint
. To understand the leveling, it is important to understand the influence of the surface tension on the paint. Indeed, the paint has two interfacial areas
, one with its substrate, one with the surrounding atmosphere. General surfactants are active on these interfaces, and depending on their chemistry, can help with the substrate wetting or be active at the paint / air interface.
The substrate wetting of a liquid
on a solid substrate is defined by the surface tension, function of the contact angle
. The contact angle θ is the angle between the intersection of the liquid-solid interface and the liquid-air interface at the three phase contact line.
- A good substrate wetting is important to reach a good paint surface leveling !
Fig: Contact Angle
Low Contact Angle vs High Contact Angle