JB weld?

[77cruiser]

How much if any affect on strength of JB when it's heated to make it cure faster?
What would be a good temp. to use?

[Kevin Johnson]

Default RE: epoxy strength vs cure time
Yes, the slower curing epoxy forms longer molecular chains as it cures which results in more strength. As to water proofing, cure speed has little or no effect, all are relatively waterproof. note that all epoxies, even the 5 minute cure type, do not gain full strength for about 12 to 24 hours depending on temperature.

When I was involved in making dentures, the slow-cure methyl methacrylate was significantly stronger and did not stain/discolor as much as quick- or fast-cure.

[Roundybout]

From their website:

“DRYING: Allow 4-6 hours for drying before handling. Allow to dry overnight (approximately 15 hours) before putting object to use. J-B WELD works faster if used in a room with a temperature above 50 F. After J-B WELD has cured for six hours, a heat lamp or light bulb placed near the weld will speed drying time.”



This is for the regular JB, not the kwikweld stuff. You can also remove it with high temps, 600 F or so softens it up for removal along with acetone for the residue left behind.

[turbo camino]

This is an easy thing to figure out. Mix up a batch, divide it in half, let one half cure at room temp and cure the other at ~150*f. They won't come out any different at all, except that you'll be able to use one of them after 10 minutes.

[Kevin Johnson]

http://www.epotek.com/site/files/brochu ... _Final.pdf

[turbo camino]

C'mon, this is JB Weld we're talking about. It's the Harbor Freight of 2 part epoxies. Heat vs room temp curing doesn't affect it a bit one way or the other. If you're using it for something so critical that it'll fail if the cure procedure isn't exactly laboratory-perfect you need to expect bad things to happen anyway. It has a place but critical stuff ain't it.

[modok]

I usually heat, I think it comes out stronger and adheres better. how hot....don't know. Depends.

May be handy to heat the work piece before applying it, that removes moisture, and the epoxy sucks into the pores better as it cools down.

The farther along the cure is, the hotter you can get it before it turns back into liquid. It will turn back liquid tho! really
So, watch out for that. Or, make use of the property. I was using it to do bodywork, playing with keeping the temperature just in the zone where I could mold it and then it would solidify as soon it cooled.

[77cruiser]

Thanks, if I average it out not much difference. When I'm in a hurry I'll continue to heat.