Ive used dermmatch and prothick for years. I do not use it on the front hairline, but i have used it on the side and temple areas. I just use it and dont really worry too much about it dying the base. after time it can, but it would change the color dark to your hair color anyway. So its not like the lace would be visible. But on the front hairline, I would be a little more cautious. because if it stains it there, u might see a dark grid pattern. The only place i would worry about staining is the very front lace on the hairline. that i would try to keep clean and not stained. reason being is because the lace is exposed a lot in this area. this is where lace is supposed to do all its magic by appearing transparent. If it does stain, then it will look like a dark grid on ur hair. So try to avoid staining that very front area of exposed lace. Other places i dont really worry about too much