I am fiberglassing a box. I had one layer of resin not "cook off". Is there any way to salvage the layer?

Question

Maybe someone can help me out here. I mixed up two batches of us composits 435 resin yesterday. I mixed 16 oz resign with 1/8 oz harderned both times. The problem is the second batch hasnt cured after 24hours. The first batch cured fine. At first I thought It was because on the second application I concentrated on a smaller area and layed multiple layers chop mat while the first was only one layer. After looking around I picked up my mixing cup from the second batch and it hadnt cured either.

My first question is there any way to salvage the still tacky layer by misting on hardener or just mixing up a new "hot batch" and laying over it?

Any ideas on how this cold have happened if both were mixed the same?

As of right now its sitting in a 95* garage with a fan on it but, I am afraid tomorrow it will still be tacky. I am still new to glassing and any insight into this situation is greatly welcomed.

Answer 1

I would try removing the multiple layers, and start over with a new batch of resin with the correct amount of hardener. Repeat this 1 layer at a time, allowing each to cure before re coating. Then top coat with a jell coat to make it really smooth.

Answer 2

Is this a polyester resin?

There are two types of polyester resin, standard and finish. The standard will cure tacky if allowed exposed to air. It needs to be covered with mold release or something else (like a vacuum mold) to get it to cure hard. Finish polyester resin contains a wax that rises to the surface as it cures to allow it to harden. I have seen people accidental get a can of each (not realizing the difference) and complain of this problem.

If this is in-fact the problem, you can coat it with another layer no problem. Use a finish resin for your top coat, or cover it with something to keep the air away from it.