Mixing epoxy

[DJ Delorie]

Experimenting with West Systems 105/205 (fast) epoxy. Learned not to mix it in a disposable plastic cup, as the cup started to melt from the reaction heat. That was only one pump's worth, too. Are paper cups safe? What do folks usually mix their epoxy in?

 

[Justin Horne]

I use a butter container. I've put 3 or 4 pumps in it once, it was fine. It also pulls right out so you can re use the container. I've been using the same one for over a month now..

 

[sandman]

I use LOTS of West epoxy.

I also build epoxy/fiberglass covered wooden boats so I usually have to do a 5 to 10 pump mix at a time.

To prevent the exothermic flash cure, use a tin (aluminum) pie plate.

It dissapates the heat faster.

sandman

 

[DJ Delorie]

It dissapates the heat faster.

When I first read about the heat cure thing, I thought "ice bath".

 

[Ryan S.]

I usually dont use too much but when I am mixing a big amount I put it in a large bowel, if the epoxy gets more than about 1/2" thick you will have a cure time of about 10 minutes and the epoxy will get very very hot. I try to mix seperate batches to avoid this and use epoxy quickly. I once needed to refit a part and had a whole bowel of epoxy mixed, so I put a paper towl on the bottom of the fridge and the epoxy on that, it sat for about 10 minutes and go very thick but did not cure, about 5 minutes back at room temp and it was flowing agian

 

[DynaSoar]

Originally posted by DJ Delorie
Experimenting with West Systems 105/205 (fast) epoxy. Learned not to mix it in a disposable plastic cup, as the cup started to melt from the reaction heat. That was only one pump's worth, too. Are paper cups safe? What do folks usually mix their epoxy in?

I mix mine (5 minute) on an index card. If one's not handy, on pretty much any piece of cardboard. I use a bamboo skewer to mix and apply. I can get just about all of it up by running the skewer along the card, flatwise.

 

[SwingWing]

Originally posted by DJ Delorie
Experimenting with West Systems 105/205 (fast) epoxy. Learned not to mix it in a disposable plastic cup, as the cup started to melt from the reaction heat. That was only one pump's worth, too. Are paper cups safe? What do folks usually mix their epoxy in?

The only times I have had exothermic reaction with epoxy is when I have loaded it with filler. It seems that when you add wood flour or fumed silica to thicken or color the resin, it is more prone to heating up and "exotherming"(Heat speeds up the cure, which produces more heat, which speeds up the cure which produces more........). one way to minimize this is to spread it out quickly and don't let it sit in a cup too long or too deep.

 

[DJ Delorie]

Today's experiment...

I mixed another one-pump batch. This time, in a 5 oz dixie (paper) cup, mostly to contain the mixing (small batch) so that I could make sure it mixed evenly. I did all my glue-ups (wow, that was a lot easier than yellow glue!) and had some leftovers, so I glued a few spent engines to some squares of plywood to make rocket stands, and added glue to a few screws-only wood joints on my jigs.

I spread the remainder of the epoxy out on a sheet of wax paper. One of yesterday's experiments was to put some epoxy on wax paper and see how easily (if at all) it came off, and it came off easily, so I figure that spreading it out will keep it from overheating, and I can just peel it off and throw it away tomorrow.

I used an "acid brush" (aka glue brush) to put the epoxy where it was needed, that went really smoothly.

So far, so good.

 

[powderburner]

Originally posted by Ryan S.
I once . . . had a whole bowel of epoxy . .

You're not supposed to EAT the stuff?

Sorry Ryan, I just couldn't resist

 

[sandman]

ROTFLMAO!

There is being "bound up" and being "glued up".

Why is bathroom humor always so funny to guys?

sandman