I've used SEM for years and whenever I've tried some other brand, It's been a disaster. You need to look at their "super white" or "phantom white". Do a Google search for "SEM vinyl" and request a free color chart. I've never found one to be an exact match for dark olive, but "bluebird green" is close. NONE of these so-called "dyes" will last if you don't follow instructions for cleaning and pre-treatment.