So I put a hot coat on my current board project yesterday and I have run into some problems. My shop is in the garage and it was about 60 degrees in there, I have been keeping all my resins and catalyst in the house at about 75-80 degrees. I mixed up about half a cup of sanding resin and had to add a ton of catalyst to get it to kick. It gelled in about ten minutes and I thought it was ok. I checked on it last night and it was very tacky and soft, when I checked on it this morning it was still tacky but had hardened up a bit, and then tonight I tried to test sand a spot and it got gummed up and looked like crap.
What do I do now? Do I have to strip this coat somehow and then add another? Can I add a hot coat to this one since its still tacky and maybe it will bond?
Whats the cause of this? Resin is only a month old.
Assuming you are using Poly; Get the temp up in the room to seventy. Carefully clean any gummies and or other residue from the spot you sanded with a very clean cotton rag and some acetone. Re- hotcoat at seventy degrees and that should do it. Room temp is the most commonly over looked and taken for granted detail on this website. Next time if you have to work in a cool or cold room use UV.
Poly resin? If yes, it is an air inhibited resin. What that means is exposure to air impedes the process of hardening. I am going to guess that you brushed it too much and disturbed the surfacing agent after it rose to the top. This is the most common cause of hot coats remaining sticky after they’ve seemingly cured. If the spots are relatively small and few in number, put some wax paper over them and let that sit in a warm (65+) environment for a day or two. If the stickiness is widespread, then you’ll have to add another hot coat and make sure you don’t repeat the same mistake. Once that layer sets up it should sand easily.
Did you add surfacing agent? If not, that is your problem.
If you did add SA I agree with SammyA. You probably brushed it too much. Get it on, cross strokes, walk it out and leave it. Too much brushing mixes the wax back into the resin and prevents it from rising to the surface.
If there are any warm sunny days left, place it in the sun for a while. This will help to harden the resin a bit before you go through the pain on sanding off your mess. Watch that it is not too hot or it will delam. Get yourself lots of sandpaper and a good block. I find that sanding the gummy resin does not load up your paper as much when you block it by hand. When you have it sanded to your liking hotcoat again.
If it’s poly resin hot coat it again and any uncured poly underneath will cure. Make sure you mix the MEKP (catalyst) in thoroughly though. If it’s epoxy you are out of luck.
Total agreement. Just gotta have a light, UV box or a reasonably sunny day. For the lam and the hotcoat the easyiest. Especially in cold temps. Just gotta have some method of setting it with UV.
I figured out one of the problems I had, my catalyst may have been bad. I ended up being able to salvage the hotcoat I did the other night because it solidified and was no longer tacky. I did some other work last night and got the resin to kick with just a little catalyst with no problems. I am going to set my fins tonight and do the bottom hotcoat. Should hopefully be done by this weekend.