Last Updated on April 3, 2023 by Dave Farquhar
I saw a question for the millionth time on a forum about what glues to use on plastic models and buildings. So I’ll cover the topic here, where it won’t get purged after 8 months.
Ask the question at a hobby shop, and the answer comes down roughly 50/50 whether to use some type of super glue (cyanoacrylate, often abbreviated CyA or CA), or some type of MEK-based plastic weld, such as Tamiya Extra Thin or the late, lamented Tenax 7R. Every once in a while, someone pipes up about the tube cement I used as a kid. You don’t want to use that stuff. If you’ve ever tried, you know why–it’s messy, dries slowly, and the bond isn’t as strong as it could be. Read on and I’ll give you the advantages and disadvantages of both alternatives, plus some secrets.
CA (super glue)
Cheap super glue works just fine for styrene models as well as resin. It’s cheap, effective, and if you need to take the model apart again, you can put it in your kitchen freezer overnight and then it will come apart easily in the morning. And it doesn’t give off obnoxious fumes. And you can glue other materials, such as metals, to styrene with it.
The downside to CA is that it’s brittle and doesn’t have a lot of shear strength. You won’t pull it apart, but you can twist it apart fairly easily.
That’s not a huge problem for models if your plastic models are going to be display pieces.
There is a plastic-specific CA available, which I’ve discussed previously. But for styrene models, it’s overkill. If you want to glue newer and more modern plastics to styrene, it’s just what you need for that, but it’s not something you’ll be doing often.
Here’s my compliation of tips and tricks for CA.
Solvent-based welders for plastic
Other plastic “glues” aren’t glues so much as they are welders that chemically melt the plastic and permanently bond them together to a single piece. They are generally one solvent or a combination of solvents, one of them usually being a chemical called Methyl Ethyl Ketone, or MEK for short.
MEK is strong and bonds styrene very quickly. And the dirty little secret is that MEK is also the active ingredient in lacquer thinner. And you can buy MEK or lacquer thinner by the quart at any hardware store in the paint section. It’s by the paint thinner. So you don’t have to buy tiny 1-oz bottles of solvent-based model adhesives at $6 a pop. Instead, buy a $10 quart of MEK, which will replace 32 bottles, and save $180. Just apply a little MEK with a small paint brush, hold the pieces together, and capillary action and chemical reaction will do the rest. The bond is fast, permanent, and strong as the plastic.
The downside to MEK is the fumes. Some people find them highly objectionable, and they’re not healthy either. Modeling master and chemistry professor Wayne Wesolowski says to always wear a respirator mask and work in a well ventilated area when using it, as it harms the liver and may cause cancer. For the same reason, you don’t want to get it on your hands. Wear rubber gloves when using MEK or another solvent-based adhesive.
What glue for plastic models do I use?
The main reason I use CA is because of MEK’s fumes. With CA, the greatest danger is gluing the model to my hand, which I can mitigate by wearing rubber gloves, which I would need to do anyway with solvent. If I glue the glove to my model, I can free my hand by pulling it out of the glove, then figure out what to do about the stuck-on glove.