Thread: A quick question re wetting out.

My understanding is that the epoxy does not fully cure for some days so you still get a chemical bond for 2 or 3 days after the last coat.

I find I need numerous coats to fill the weave completely and I don't sand between them unless there are already enough coats to provide a buffer against sanding through to the glass.

My opinion is that assuming you only did the repair yesterday your best course is to get a thin fill coat on ASAP and then follow up daily until happy with the result.

Epoxy (depends on the hardener and environmental conditions) will be past is chemically active range from 12 to 24 hours. Fast hardeners sooner, slow or extra slow hardeners later. I consider all epoxy formulations cured after 18 hours and assume I need to wash any potential blush off, then "tooth" the surface for the next coat.

You don't have to grind down into it, just a good 80 - 100 grit scratch is all it takes. You just want to knock the shine of it and add a scratch, for the next coat to "key" into mechanically.

Add some balloons or other light weight filler to this coating, so you do fill the weave, in one shot.

Thanks for the replies, guys. I ran the cabinet scraper lightly over the patch, then put another coat over the top to fill the weave. The original epoxy was about 19-20 hours old, but with some cool overnight temps (9-10 degrees c), it wasn't fully hardened, so hopefully everything will be ok, and there will be a sufficient bond.

Epoxy cure rates can be all over the place, but the rule I use is the thumbnail test. If you can easily dent the fresh, but dry coat with a thumbnail, it's still chemically active and you can over coat without sanding and rely on a good chemical bond. If you have to push fairly hard to make this dent, technically it still may be chemically active, but I don't trust it and will wait until it's like rock and sand, knowing I'll have a mechanical bond instead.

Boats are full of mechanical bonds, so nothing to work about, just a little extra work. Since it was relatively cool, you'll probably be safe. The reason I'm so cautious about this is simply, most folks don't have good environmental controls, so their coatings are prone to blush, dust, dirt and suicidal bugs. Given this, most DIY coatings need some "dressing" before the next coat goes down.

Thanks PAR. The epoxy was a little harder than you describe, but still way too soft to sand. I'm quietly confident that it will be ok. Hopefully by giving it a light scrape over the top of the weave, there will be a mechanical bond if there is no chemical bond.