Hardening 2-part epoxy

JeffBond · Post by **JeffBond** » Sun Jul 01, 2007 3:22 pm

I'm getting to the final stages of my PL Refit and I have most of the Trekmodeler lighting kit installed and a stand built--the model will be supported by a 5/8 inch brass tube, and the lower part of the lighting kit power connector is lodged inside the top of that pretty well with just a little bit of 2-part epoxy--it ain't goin' anywhere.

The problem is the UPPER connector. This goes through the bottom of the Refit's lower hull right under the arboretum--there's a nice little "tub" there created by the wall supports that the arboretum floor piece sits on. I drilled out a hole for the connector plug, twisted it in place, then poured two-part epoxy around it and mixed it so I could get a rigid support around the plug, which is basically what the lighting kit instructions recommend.

The problem is the epoxy is taking a LONG time to harden--a lot of it is fine, but there are areas that are still soft--when I apply pressure I can see stuff bubbling around inside the seal and there are tacky areas on top of it. My question is is there any way to accelerate the hardening process--it's been over a week since I poured this stuff. There's about a half inch of epoxy around the plug at the deepest point so it's expected that this might take a while to harden, but my question is how long SHOULD this take to be able to support the weight of the model, and is there anything I can do to accelrate the process?

Dakota_in_the_sky · Post by **Dakota_in_the_sky** » Sun Jul 01, 2007 4:51 pm

I've never heard of epoxy taking so long to dry. All the brands I've used dry very quickly. I think you have a bad batch, or it wasn't mixed equally.

The best thing to do is rip as much of it out as you can and start over with a new batch.

Is this epoxy resin or epoxy putty?

JeffBond · Post by **JeffBond** » Sun Jul 01, 2007 7:47 pm

It's not putty, it's clear mixable epoxy glue. It's been plenty hot here and I've heard heat can soften epoxy although I don't know if it does it once it's set...

Dakota_in_the_sky · Post by **Dakota_in_the_sky** » Sun Jul 01, 2007 8:17 pm

JeffBond wrote:It's not putty, it's clear mixable epoxy glue. It's been plenty hot here and I've heard heat can soften epoxy although I don't know if it does it once it's set...

If part of it hardens and part of it doesn't, it's suspect to me. You would be better off getting rid of it. You don't want something soft on your model affecting the paint later on.

The heat might affect the epoxy, but it would probably affect it evenly. Since it's a two part epoxy, the chemical reaction will force it to dry. It doesn't matter if its the bottom. It could be it wasn't mixed thoughly.

USSARCADIA · Post by **USSARCADIA** » Mon Jul 02, 2007 2:59 pm

It could be unequal amounts. The twin tubes from Home Despot have a habit of squirting out one of them pre-maturely. You have to wait till they come out equal before starting a pile you can mix. Same thing can happen to Bondo in the can if mixed improperly, it never hardens.

JeffBond · Post by **JeffBond** » Sat Jul 07, 2007 6:50 pm

I dug half of it out, thoroughly mixed the next pour and got much better results...thanks for the advice everybody!

DX-SFX · Post by **DX-SFX** » Sun Jul 08, 2007 3:46 pm

Poor mixing sounds like the problem. Epoxy comes in all sorts of set times from five minutes to twenty four hours. Some commercial epoxies need baking in an oven to fully cure but you're unlikely to encounter those. Once the epoxy is mixed, don't let the temperature drop below five degrees or it will never fully cure no matter what you do to it.