Ask the Expert Question-and-Answer Archive

by Ron Joseph

August, 2001

Definition of "High Solids" Coatings

Q. I along with my colleagues had the opportunity to attend your seminar in State College, PA in 1996. I often refer to the notes from that course. So naturally I looked through that information and could not find an answer to the following question.

What is the definition of a high solids coating?

Thank you in advance for your help.

A. Thanks for writing and for your kind comments.

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".

Hope this helps.