Originally Posted by Celestialsailor
Maybe I'm wrong but I have noticed the whiteness on the rag and the gelcoat feels a little sticky when I have used it. Also tried once to remove some black streaks of unknown origin off the gelcoat, only to have it stain into the gelcoat slightly.
If I was to remove a "goo" from gelcoat, I would be more apt to use a more petroleum based product like "goo gone".
Your rag should be coming back spotless off clean gel. If it's not it's either paint
or there's a very big problem. Sure you're not just seeing the dust and dirt you might be wiping? I wipe for prep with acetone all the time, the surface is already spotless and the rag comes back clean every time. The wipe is to make sure all dust is gone and evaporate any moisture. If you have porous gelcoat then trying to wipe any sort of goo off of it with any solvent will wipe it into the pores, leaving pinhole stains that can't be removed. But that should be the only way possible to wipe black streaks into your gel. Petroleum products are the worst way to go, they take much too long to evaporate and leave a residue. Alchohol is the safest solvent for wiping gelcoat, followed closely by acetone. Xylene is great for removing adhesive
residue, but make sure to wipe it clean and dry with acetone as soon as you have the residue off.