Epoxies for assembling models?

DeltaVee · Post by **DeltaVee** » Tue Nov 11, 2014 10:29 pm

I searched and found not very much other than 'some epoxies damage plastic."
I've got the new StarCraft Valdore and want something better than CA to glue the main wings. They're too thin to pin. I looked at 2 part epoxies at the hobby shop today but not sure what to use or how to use it. Is it a lot better than CA? How can I remove excess while it's still pliable? Do I have to rough up or smooth out the mating surfaces? ... And so forth...?
Advice?

Kylwell · Post by **Kylwell** » Tue Nov 11, 2014 10:53 pm

Roughing up the mating surfaces never hurts. Even the thinnest of pins greatly increase the joint strength.

With resin I've used everything from Aves (Fix-It & Sculpt) & Gorilla epoxy without issue. With the Aves, and green stuff, you can press the 2 parts together, trim & smooth the excess and let cure.

DeltaVee · Post by **DeltaVee** » Wed Nov 12, 2014 6:12 pm

Thank you, sir. Anyone else done well with any other brands of epoxy? I noticed some basically go back within a few days of opening and others are fine for weeks in the fridge. Not exactly much shelf life.

Joseph C. Brown · Post by **Joseph C. Brown** » Thu Nov 13, 2014 10:03 am

Various Devcon-brand epoxies (5-Minute Epoxy, 30-Minute Epoxy, 2-Ton epoxy), all work well with resin models, in my experience. Make sure the surfaces to be glued are freakin' CLEAN! A downside is that the remaining un-used product really doesn't store well, so consider 'production lining' some builds to match the glue supply is worth considering.

And, just be sure you are completely set up and ready to rock once you start the mix process. Doing a full dress rehearsal / dry run would be an excellent idea. Adequate ventilation is highly desirable as most of these stink to varying degrees.

An additional alternative is Magic-Smooth from Wesco. It's a two-part mix that is little thicker than Vaseline, and, yes, it is messy to mix and apply.

That being said, it has a 45-minute working time after mixing, it cleans up easily with water, and when cured (overnight) it will not shrink and it's an awesome adhesive. It is also foam-safe, so using it on resin is no problem.

DeltaVee · Post by **DeltaVee** » Thu Nov 13, 2014 10:06 pm

Thanks very much. Sage advice. I've seen epoxy "minis" at the hobby shop that I'll likely go with. The best I'll be able to do on the Valdore is getting subassemblies together for painting and then gluing those and painting the joints in a second round.

Cleaning with 409 or bleach or thinner?

Should it be applied as thinly as CA, i.e. if I press the joint tightly this stuff if it's thicker will just squeeze out?

kenlilly106 · Post by **kenlilly106** » Fri Nov 14, 2014 6:29 pm

sbaxter · Post by **sbaxter** » Sat Nov 15, 2014 6:24 am

Just wanted to point out that the JB Weld site has a FAQ with some useful information (see http://www.jbweld.com/faqs/ ). One point it makes (rather strongly) regards the use of surface cleaners prior to use, stating "We recommend using acetone or lacquer thinner. In the absence of these two, soap and water can be used. Just be sure that the surface is completely dry before applying J-B Weld. DO NOT use alcohol or any “cleaner” that will leave a petroleum residue." The prohibition against using alcohol was a new one on me, but I'll follow it in the future. The page also says the product can be thinned with acetone or lacquer thinner to make it flow. Says you can add up to a teaspoon of either per one two-ounce package.

kenlilly106 wrote:I don't like the standard 5-minute epoxies because while strong they don't set hard in my experience and that can cause problems with sanding and painting.

I've noticed the same thing. In addition, I don't typically care for the short working time. If I need an epoxy and also a quick bond — presuming the surface is large enough for this — I'll use the epoxy and a dot or three of Gorilla Glue Super Glue Gel. The latter bonds in 30 seconds or less, and is strong in and of itself, and then it will hold while the epoxy sets.

kenlilly106 wrote:Placing masking tape on either side of the joint will help to protect nearby detail from getting covered by the epoxy, if I have a lot of squeeze out I will scrape off the worst and then use nail polish remover to clean up the remaining before it sets solid

That works well. Another trick I recently picked up here in another thread was to use the masking tape as you mention, and then wipe away the excess (and also possibly force the epoxy back into the area of the join) using a bit of wax paper wrapped around your finger or a smaller tool. Just don't forget to remove the masking tape as soon as you can so it doesn't get epoxied to the model!

Qapla'

SSB

DeltaVee · Post by **DeltaVee** » Sat Nov 15, 2014 2:09 pm

Very helpful and good catch. Is there anything in injection plastic, resin or vinyl models that is polypropylene or polyethylene? Says it won't work for those.

sbaxter · Post by **sbaxter** » Mon Nov 17, 2014 12:31 pm

DeltaVee wrote:Very helpful and good catch. Is there anything in injection plastic, resin or vinyl models that is polypropylene or polyethylene? Says it won't work for those.

Some toys are made with these types of plastic. Many are reporting success by applying an adhesion promoter spray (from an auto parts store) to the plastic (after a good cleaning), and then painting with various products as a primer. Over on the Star Wars board here, jaitea has used an adhesion promoter and a gray paint made for plastic car bumpers on a new Millennium Falcon toy that appears to be made of one or the other of those plastics, and found success. See here: http://www.starshipmodeler.net/talk/vie ... p?t=113542

I'm not sure whether an epoxy would be the way to go on these plastics (after using an adhesion promoter), or if something like Gorilla Glue's super glue gel would be a better choice.

Qapla'

SSB