Respectfully, IMAC...that's not the right way to do it. YES, you paint the base colors first, but no, you do NOT have to mask off all the individual squares with tape, liquid mask, or anything else. Get the article, read the text and photos, and it will tell you how to do it right in two steps.

I won't "diss" claude mccullogh, he's one of the greats. But if he is painting one square at a time, he has wasted an awful lot of time over the years. I did not see his article, so I do not know...