The Resin Didn't Kick !

[senormechanico]

I am repairing some piling caps and I made the mistake of using some rather old resin.
I didn't have instructions, but think I put plenty of catalyst in it.
It never hardened.
Now I have four piling caps which have been sticky for two days while stinking up the house.
We've put them in the bathroom with a couple of heat lamps, but still no joy.
I suppose I could try a heat gun, and watch out for smoke.

Any suggestions would be greatly appreciated !

[SabreKai]

In general I'd say your catalyst has expired. The resin is usually good for decades if kept cool and dark. I know this because I bought 5 gallons of west system 105 in 82 and was still using it to do work on an electric racing car in 95. Sometimes the resin will crystalize, but warming it up will break them down. New hardener. Scrap off the failed attempt, wipe it down with acetone and reapply new. However, don't take my word for it, do a test batch first. I always do. Mix it up in a yogurt tub or paper cup or what ever, in the smallest batch you can accurately mix with new hardener. Ignore it for a day and then see if its hard.


Sabre

[djmarchand]

I agree, more likely the catalyst than the resin. You can try painting the surface of the tacky resin with new catalyst.

But some resins are designed to be tacky so you can put a subsequent layer with good bonding. If the cayalyst paint job doesn't work then a new layer of finish resin with good catalyst should work.

David

[capngeo]

Polyester, vinylester or epoxy?

[senormechanico]

The 1 qt can doesn't say what type, just "Add 30 drops of hardener per 4 oz of resin.
It will harden within 30 minutes @ 70f."
I suppose it's polyester.

[djmarchand]

That ratio sounds like polyester. Vinylester is just a variation on polyester and uses the same type of catalyst.

David

[Boracay]

Is it possible that the you are adding old accelerator to precatalysed unsaturated polyester resin?

I'm only guessing but scrapping off all possible uncured resin and painting on some fresh accelerator (promoter...) could start it all going.

My understanding of polyester chemistry is that it is precatalysed but the reaction is normally very slow. Adding accelerator is what causes the resin to harden.

Warning: Do not add accelerator to catalyst as a very rapid reaction (sometimes called a kaboom) may result.

Not having used much polyester I'm only guessing but some may not cure in the presence of air (to facilitate lamination).

[Wand]

Originally Posted by senormechanico

I put plenty of catalyst in it.
It never hardened.

This may sound strange but if you've put too much catalyst in it will always remain sticky - even with extra heat etc. This I do know I suggest a test with the same materials but this time measure accurately. If the materials are then found to be okay, you'll need to clean off as above and start again.

[sabray]

not a solution but it will make you feel better. Fella next to me was trying to smear microlight all over his boats underside. The stuff was fireing like a popover in the can. So he changed up the hardener ratio. This worked a dream and he was able to smear stuff around 30' of full keel bottom. Problem came in days later as he could still smear the stuff and it wasn't hardening.
hope that made you smile at least

[sww914]

I've used polyester resin that is several years old with new hardener without problems. I've tried new resin with old hardener and it never kicked. Old hardener isn't worth the risk, IMO. It's about $2.00 for a new tube. I will never, ever apply resin of any type when the temperature is declining, it almost never works.

[SurferShane]

Bugger, I have had the same thing happen many times using polyester resin fixing surfboards. Sometimes it was old hardener and other times moisture in the foam or filler. Eventually I have found it will harden maybe in a week or more? Till then I would be putting them somewhere well ventilated. Other solution is to start again!

[s/v 'Faith']

You could always try mixing a second batch (with new catalyst) and applying it right over the top. Nice thing about good old fiberglass is that unlike epoxy the resin will kick without being fully mixed (sets up in the presence of MEKP). Might be worth a try, if it fails, then you just have a bit more product to clean up.

Good luck.

[senormechanico]

We tried "painting" a layer of new catalyst over the resin and leaving it in a heated space (a bathroom with a couple of heat lamps).
Hours later, no change, so I tried using a heat gun with the bathroom fan on.
The fumes were unbelievable.
I could see a little bit of bubbling happening as I moved (or was that the fumes playing tricks with my brain?).
It seemed to help a little.
We left it to sit overnight with the fumes captive in the room and the fan left on.
I'll try painting another layer of new resin and hardener tomorrow morning.
Thanks for everyone's help.
The mystery continues...

Steve

[senormechanico]

(A day later)

All the resin has pretty well set up. Not tacky to the touch, but still slightly soft.
In a few days they should be ready for sanding and paint.
Thanks to all.

Steve

[delmarrey]

A couple of days ago I quit doing any glass work on the boat. The weather is cold and wet enough now that the epoxy and polyesters are taking to long to set up (2-3 days).

I once laid up 30' x 2' - 6 oz glass with epoxy that had the wrong mix (got the wrong pump) and it was a real job trying to get it all off. It sat for a week and just became gummy.

You got lucky! When you can run the sandpaper over it without it loading up the grit, then it's ready.

BTW- if you get polyester too hot it will catch fire. I have an acquaintance who lost his boat to a fire by leaving a heat lamp over some interior polyester work.

I only use epoxy for interior work unless I can run a fan on a warm day. And then I'll use a respirator to do the work.