how cold is too cold for resin?

alick burt · Post by **alick burt** » Thu Oct 04, 2007 7:17 am

Just how cold is too cold for working resin?
I have the west system 105 resin with 206 hardner.Is this going to lead to an opaque finish?
My workshop is a 20ft by 60ft corrugated shed which currently has no heating and is at a temperature of 15 degrees c.(60F)..It's a sunny lunch time.
do I need to raise the temperature with some fan heaters and or heat my resin in a box and my hull with an electric stripping gun.
I still have a bit more sanding etc to do before i'm ready and the weather forcast for the next few days is good.
If i need to I will leave it till next spring but I'd rather not as it looks so good so far..
Any thoughts or comments including laughter welcome!
regards
Alick :smile

Rick · Post by **Rick** » Thu Oct 04, 2007 8:57 am

I had problems with another epoxy brand at 12C, even though it was advertised that it could be used at 10C.... the epoxy cured OK, but there was also milky blushing which was unexpected..

At 23C, for the actual application, wetout and additional coats, there was no blushing, no problems, and everything was fine.

So my rec is to play it safe and apply the epoxy at a warmer temp if possible... the West epoxy that's most often used IIRC, will have problems at cold temps and could absorb water from the humidity that's often present at low temps causing milky blush, and there could be cure time problems as well. They recommend using their low-temperature epoxy to avoid these, if this must be done at low temps..

The temperature requirements are important at this stage, and the instructions should be followed closely... and maybe a test panel done first, to avoid any problems with blushing or humidity creating a milky appearance... anyway, good luck, I suppose the old "better safe than sorry" applies here.

Post by **Patricks Dad** » Thu Oct 04, 2007 9:13 am

West system 206 hardner is not intended to be used for clear coating... caution.

207 is intended for that purpose.

alick burt · Post by **alick burt** » Fri Oct 05, 2007 5:58 am

Thankyou for your replies
I guess I'll have to wait till next summer but I am going to experiment with electric fan heaters. Is it true that I only need to get the temperature up for a day or two whilst I work and curing takes place?
Why oh why did I get the wrong hardener?!!!Arrgh. :shocked
such is life!
Thanks again
Alick

Rick · Post by **Rick** » Fri Oct 05, 2007 10:00 am

Alick, I didn't use West epoxy, and let the temps cool back to 12-15C after the last coat hardened, more or less, with no problems afterwards. I'd still test the West epoxy to be sure. For me the blushing from cold temps and high humidity happened before the epoxy hardened.

cecbell · Post by **cecbell** » Sat Oct 06, 2007 8:15 am

Alick,
As I understand it, the reason 206 isn't recommended for clear finishing is because it has a tendency to cloud up if applied in too much humidity. I built two canoes (that were painted on the outside) using it and it never clouded. The inside, which is not painted, remains perfectly clear. On the other hand, I met someone who ended up painting his canoe because he got caught with high humidity and it did cloud. You may be OK if you avoid using it in high humidity but I have no idea how much is too much.

If I recall correctly, the lowest recommended temp. for using 206 (and 207) is 60F (15C). I wouldn't hesitate to use it at that temp. for bonding but it's too thick to spead well for wetting out. I don't try to apply a wet out coat at less than 23C and 27C is even better. In any case, it's best to treat it as if it were blushing even though none is visible.

Post by **Patricks Dad** » Sat Oct 06, 2007 8:29 am

I accidently used West 209 hardner on the inside of a prior canoe. It also is not recommended for clear coating. I called West Systems support and the guy there (very helpful) told me that I was probably OK but it could possibly get cloudy (not a blushing phenomenon) over time (not an immediate event) depending on the humidity at the time of application. The formulation of the various hardners is very similar but 207 is the only one they can be certain won't cloud. They do lots of tests trying to make their epoxy cloud to understand it and they can successfully cloud witih non-207 hardners. They have to work at it however.

For piece of mind, my advice is, if possible return the 206 and exchange it for 207 (if that's possible and doesn't cause you any big hassles). I'm not sure I would buy a whole new batch of 207 if I had to pay for it all over again.