Resin systems typically used in solvent-based coatings are incompatible with water due to the high surface tension (72 dyne/cm) of water. Therefore, replacing solvent-based coatings with low VOC water-based coatings presents a challenge to coating formulators to overcome the water incompatibility problem. To meet this challenge water-based coatings are more complex than corresponding solvent-based coatings. In order to get some insight into the major difficulties coating formulators are facing to develop low VOC coatings, SpecialChem asked its members in January: Which of the following is the biggest challenge to overcome when developing a low VOC coating?