West System Melt Down!

[unbusted67]

So I was laying down some base coats of West Sytem Epoxy with 207 hardener today onto the rails that go around my boat and I was doing it with some cheapo foam brushes, 1st bad idea. I plowed through all of my foam brushes within the first two hot coats. I had painted myself onto my boat which was up on a trailer, I had prepared for this, brought my book and all of my painting supplies...except for spare brushes. I rooted through my tool bag looking for a brush and found one that I had used with varnish that I had cleaned with turpentine and soap. I got about three quarters the way around the boat and I started noticing that my paint container was extremely hot. Then I noticed it was smoking. Then the dog started barking next door. Then my girlfriend started calling, twice, back to back (I it when she does that). I picked up the phone and barked at her and when I hung up and looked down I found I had a nice big fat brick of completely hardened epoxy in my paint container. This happened over the course of maybe 30 seconds. Weirdest thing ever. Needless to say I have some sanding to do before I go on to varnish.

[colemj]

Not weird - a regular occurrence for me. Sometimes you just don't guestimate the working time correctly when you make up a batch...

Mark

[Pete7]

You owe your gf a large bunch of flowers because if you had continued to use the epoxy once its started to cure it leaves big blobs of resin all over the work surface and makes a right mess. Don't ask how I know

I now use small amounts in a shallow cooking tray, wasted too much resin with hot mixes over the years.

Pete

[unbusted67]

Yeah but every other pot that I made did not set up until well after I got all the way around the boat. The pot was really smoking too, and was really hot. I am attributing it to something that was on the brush that I had used with the varnish.

[witzgall]

That's what happens when epoxy cures. Exoxy, if i remember correctly, causes an exothermic reaction, give off heat as it cures. It also cures faster, the hotter it is. Add the two together and POW!

You can avoid this by using the slow hardener, and by mixing smaller batches. Or both.

Chris

[unbusted67]

No dude you don't get it. This one batch freaked out and it was because it was contaminated.

[FrankZ]

I have had the same happen.. made a mistake of making too much with the fast hardener on a day that was hotter than I thought it was. Got all the bolt holes filled, then realized I missed one. Reached for the pot and it was hot and smoking.. over the side it went (onto the ground not into the water).

[unbusted67]

Yes! I have used West System hundreds of times with lots off different hardeners and I have never seen anything like this. It just took off on me. It was piping hot right before my girlfriend called.

[s/v Jedi]

I once prepared a batch by putting a small amount of resin in a plastic throw-away cup. Some time later I came for it to add hardener and use it but it was one smoking hot pile of half cured epoxy. Apparently something in the cup reacted similar to hardener.

The way I understand it with epoxy is that the hardener isn't hardener at all. Epoxy resin will cure by itself but they do something with it to prevent that from happening. The hardener attacks and takes out that something allowing it to cure.

I am not surprised at all that a used brush with varnish turpentine and soap residue will do what it did because there's enough chemicals in that mix ;-)

So I now mostly use the official mixing pots, sticks etc. I have about the complete West System catalog of items aboard incl. their syringes (had an adventure with one from a pharmacy before), spreaders (had a project ruined with another one when all the yellow came off onto my project) etc.

cheers,
Nick.

[David_Old_Jersey]

The epoxy melted through one "make do" mixing pot .........fortunately I was at home in the garage when I picked it up

[unbusted67]

I totally blame myself for that one. I love West Systems epoxy. You can do anything with it. I even fixed my head with it today with whatever was left in the pot. I don't know how tough that 207 stuff is but I painted it on some fiberglass and stuck it to the bottom of our little camper head. We'll see how she holds!

[hummingway]

I built a canoe and had one of thebatches do that. At the time I thought I had put too much hardner in but maybe it was contamination. I wished it would do that the other day when my duct tape dam gave out and the epoxy was flowing places it would be better it didn't flow!

[David M]

"duct tape dam"...cool! One more use for duct tape.

[Randy]

I've been doing a fair amount of epoxy lately and have been complaining to myself about how slow it kicks off but I'd rather that than the pot meltdown.

[witzgall]

With respect, I doubt that anything on your varnish brush caused the epoxy to kick earlier than is would have in an "uncontaminated" situation.

The less surface area for a given amount of epoxy mixed, the faster it will harden. They don't call it a runaway reaction for nothing. The expoxy cures, and heats itself, which causes the exoxy to harden faster, which heats the epoxy more, which causes it to harden quicker, which...

Chris

Originally Posted by unbusted67

No dude you don't get it. This one batch freaked out and it was because it was contaminated.