Boat Building Forum

Find advice on all aspects of building your own kayak, canoe or any lightweight boats

Epoxy: application problem *PIC*

I'm having an issue with MAS resin and slow hardener. In the photos you can see that the epoxy appears to have pulled away from some areas while curing. I had this happen on almost all of the underside of the deck. The photos are from the inside of the hull. Here's what I did:

I sanded the entire inside of the hull with 120 grit sandpaper to even out a previous coat that was uneven. That coat was applied a week or more prior. After sanding, I scrubbed with a grey scotchbrite pad and water, no soap. I vacuumed the dust, wiped with a damp paper towel then a dry paper towel to remove remaining dust. I mixed small batches (no more then 5 pumps each) and mixed thoroughly in a cup. I poured the epoxy into a roller pan and rolled it on with a foam roller working in about 2' sections, tipping off with a foam brush. Once I had the entire surface coated I looked it all over to be sure everything was covered. I was working in an open garage on an 80F+ day.

On the deck I mixed a larger batch. I thought maybe I worked too slowly and the epoxy started to kick before I got everything covered. That's why I used several small batches on the hull.

I also wondered if it could be a contamination issue with the resin or hardener but I applied the last fill coat on the underside of the deck (after a lot of sanding) and didn't have the issue using the same procedures.

Has anyone else experience this or have any suggestions? I'd like to figure this out before I start putting fill coats on the exterior.