Mike Marlow wrote:

I too have thinned a lot of coatings that say "Do Not Thin" with
problem-free results. I suspect the advisory is more to address potential
running problems if thinned and applied in other manners than a spray
finish, than anything else.

A technical rep for a famous purveyor of pro finishing products starting
with "M", and ending with "k", told me "Do Not Thin" was entirely
related to VOC regulations. He then went on explaining why we should
ignore the instruction. G