Epoxy Exothermic Dangers

[68Bud]

Hey Everyone,

Today I mixed a 1 pump batch of West Systems 105/206 in a small cup like I have countless times before. Stirred the mix, then started brushing on the glue. After about 20 minutes the batch got a skin over it so I pulled the skin to the side of the cup and worked a little more with the liquid epoxy underneath. I got preoccupied with the clamping of the parts for probably 10 minutes or so and when I looked up the cup was SMOKING! My first reaction was to remove the cup from the shop, but I knew it was too hot to touch so I grabbed a pair of pliers and took it outside. After reading this thread I'm feeling pretty lucky.

http://www.thehulltr...exotherm.html#b

I never knew epoxy could catch fire! I have been building wood boats for close to 30 years and have never had this happen before.

Learned something today, just wanted to pass it on.

Scott

 

[57fairlane500]

I have had it happen a number of times. Did you do full pumps from both? If so then it is time to replace the pumps as they are probably out of calibration. Or is one of the cans getting low, as you might have gotten some air instead of liquid.

 

[Hydro Junkie]

Epoxy can catch fire quite easily. It can be such a hazard that, when I was working for US Marine in Arlington WA, they actually held training on what to do if epoxy did catch fire. Since the plant I worked at produced $500,000+ yatchs, one going up in smoke could potentially cost the company several million dollars if one did catch fire and spread to other boats or, for that matter, the buildings themselves

 

[Patrick M]

I've been using West Systems epoxies for about 15 years and consider it normal for any leftover mass to exotherm...... almost always with 205 hardener and less so with 206. The ambient temperature has a lot to do with the tendency to smoke, anything over 80* F will accelerate both cure and exotherm, so I usually keep a bucket of water handy to drop small mix cups into. Ambients of 95* and above make 209 hardener a near necessity, but then I hate waiting for it to cure......

 

[dwilfong]

peroxide and colbalt reactions can be quit volatile.

When I was 19 one of my first jobs was fiberglass fabrication. We would mix our own 55gal drums of different resins. Back then the peroxide would come in a 50% solution.

I would mix the cobalt in the drum with some coppernaphamate.

The peroxide and the cobalt had to be keeped in a box buried in the ground 100' from the shop and 100'apart from each other.

The old hippie that owned the place showed me what would happen if you mix the two in full strength once. Little prox on the floor and one drop of cobalt on it. POOF it looked like a small nuclear explosion. Need less to say I was real careful with the cobalt after that.

Had many a cup go up in smoke. had a can just to put hot mixes in.

David

 

[Jim Caldwell]

I quit using the pumps years ago because they go out quickly.

When it is hot in the shop and I am out of slow hardner I put the Resin not the hardner in my small frig. over nite.

The cold resin will buy you some time on the cure schedule.

I would rather mix another batch than mix more than I can use in 5 mins, the more mass the faster it will kick off!

 

[SayMikey]

If you put it in a larger container say a 3 ouch cup it will go longer spreading it out slow the kick. I weigh mine and can save by not wasting it

 

[Greg Hahn]

Thinning the mix with de-natured alky will also slow the cure and make it spread much easier.

 

[MikeP]

In hot weather or if I need a longer pot life I mix it and then pour it onto a small paper plate.

Mike

 

[68Bud]

If you put it in a larger container say a 3 ouch cup it will go longer spreading it out slow the kick. I weigh mine and can save by not wasting it

Thanks for tips guys.

I like the weighing idea. I think the small cup I was using combined with a high ambient temperature is what caused my batch to overheat.

It actually boiled and captured the bubbles! Freaky!

 

[Kez]

Hi Scott,

A couple of years ago I needed to add weight to the bow of a shovel nose hydro. I dropped 10 oz of BBs and then pour epoxy thickeded with micro ballons to set the weight. I had about 2 oz of epoxy but that was enough to generate a lot of heat. Polyester resin is worse.

kez

 

[RobertWurster]

yup ive had 5 min epoxy get real hot.and melt the cup i was using,never had a problem with mass tho.Just shows you can never be to careful,

 

[anthony_marquart]

I have had it turn into a boiling cup of lava also.. pretty dangerous really.

 

[tnrcboatracer]

The smole emitted by an exotherm is highly neurotoxic. When I worked in the aerospace sector, we had evacuation drills to prepare us in case the resin lab in our building had an exotherm. At the time we said that the smoke could give you the IQ of a PB&J sandwich. Very nasty stuff.

BTW, with epoxies increasing the hardener does not increase the cure speed/exotherm. VArying the ratio does affect the cure speed/exotherm of Polyester/vinylester resind. Both PE and VE use catalysts, Epoxy uses a hardener/curative.

 

[Jeff]

I have used a small baking pan about an 8x8 with ice and a little water in it to set my mixing cup in when the shop was hot.It gives a little bit more working time.I used plastic cups so the water didn't soak in,just watch for water drips on what you are working on.