What is the definition of a high solids coating ?
There is no true definition of "high solids". In paint and coating circles "high solids" coatingS are generally solvent-based coatings that comply with regulatory limits, such as 3.5 lbs/gal. As you will probably remember from the training program, a coating with a VOC of 3.5 lbs/gal has a volume solids content of "approximately" 52%. That is hardly "high", but it is higher than was available in the 1970s. Currently, coatings are available with higher solids contents, even up to 80%, and for UV curables almost 100% (after the catalytic reaction).
Waterborne coatings which are regulated differently from solvent-based coatings can have solids contents well above 30 or even 40% and are also considered as "high solids".
