The Combat Workshop‘s “Sprue Cutters Union” is akin to a group build, only with blog posts instead of builds.
This week’s topic:
What glue(s) do you use – and how do you apply them?
In the beginning, there was Testors tube cement. And it was terrible.
Growing up, I used all of the “standard” modeling glues. The aforementioned tube cement. Testors Liquid Cement, which was a little bit better, but not much, because it still took a while to cure, and because I had no idea what I was doing. My favorite glue around the time I wandered away from the hobby was everybody’s favorite “when you absolutely, positively have to stick two pieces of anything together” adhesive – cyanoacrylate glue.
From the moment I first came back to the hobby, around 3.5 years ago, my go-tos and methods have changed completely. Gone is the tube glue – or any Testors products, for that matter. Instead I rely on a hodgepodge of options depending on what’s being glued, and when in the build.
Liquid welders. Liquid cement. Solvent. Call it what you will, this class of adhesive all works the same way, by literally welding plastic together.
Welders aren’t adhesives so much as chemical brews that melt polystyrene for a short period of time. Stick the styrene together, and when it re-hardens, viola, you get one hell of a strong join.
Testors Liquid Cement is the weak sauce version of this kind of welder. When I came back to modeling, I started using a higher-strength welder called Tenax 7R. The difference was downright revelatory.
With Testors, you’d brush it on, then wait. And wait. And wait.
With Tenax, you apply a tiny amount to the join you want to weld, wait maybe 15 seconds, and boom, it’s done. This stuff goes so fast that actual gluing is probably the fastest part of any build I tackle.
Tenax – like most solvents – is very thin and ultra-low viscosity. Not exactly a superfluid, but touch it to a seam and it will race down the length of that seam like nobody’s business. As such, a little goes a very long way. The trick, I’ve found, is getting the application right.
Personally, I use two methods. The Touch-n-Flow and the Microbrush.
The Touch-n-Flow tends to freak out modelers who’ve never used one. But it’s really very easy. Basically a glass tube with a metal syringe tube affixed in one end, the Touch-n-Flow uses a solvent’s capillary action.
To fill the Touch-n-Flow, all you have to do is put it into the bottle, then use suction to draw solvent up into the tube. Some people do this by literally sucking on the thing like a straw, which is crazy. I’ve found that a baby snot-sucker thing works much better.
Once you’re loaded, just lightly “draw” the Touch-n-Flow across the join like a pen. Keep a light pressure and steady pace…the goal is to create a uniform “bead” of solvent. Sometimes it’s great to hold the join together with light pressure as well, then increase pressure once the solvent is in place. When you have little spikes of melted plastic bubble up, you know you’ve got a great weld.
If the Touch-n-Flow clogs with plastic (and it will), just set it into the solvent for a few seconds. The plastic will dissolve and you’ll be good to go again.
As awesome as it is, the Touch-n-Flow has one glaring flaw. It downright sucks at edge joins (like top-and-bottom wing halves). The syringe tube is prone to jumping and getting solvent in places you maybe don’t want solvent in.
For these edge joins, I use a yellow microbrush instead. It works extremely well for applying solvent, so much so that it’s what I generally use now for most all out of sight welds, as well as for edges.
Methyl Ethyl Kickass
Last fall, Tenax failed me for the first time. After working extremely well on probably 30 builds, it showed rather poorly against the plastic Revell uses for their new 1/32 Bf 109G-6. To my horror, I found joins separating and welds just not biting the way they have on every other kit I’ve built.
I’d read somewhere that all of these solvents are basically just methyl ethyl ketone, or MEK. So…I had a bottle of MEK…poured a little into a smaller jar. Oh my god. It’s basically Tenax, but hotter. And far, far cheaper when bought by the quart.
Since I tried it out on the G-6, I’ve used MEK more or less exclusively on my builds, including the Ki-84 and my current ongoing builds, the Tamiya Challenger 1 and Trumpeter Me 262A-2a.
Considering the ongoing panic about Tenax going out of production, and the price of similar substitutes, I foresee sticking with MEK for a long time.
Protip: Treat this stuff with respect. It’s very toxic so try to avoid contact with your skin or making cocktails with it. I don’t know that it requires a full-on respirator considering the very tiny amounts being worked with at once, but if you’re the hyper-cautious sort, wear a respirator too.
My use of cyanoacrylate – or CA – has fallen off dramatically since my discovery of powerful solvent glues, but it still has its place. These days, I use CA to:
- Glue resin, brass and other non-plastic materials to plastic and to each other
- Glue small items that will be under tensile (pulling) stress, such as biplane rigging or cockpit bracing wires
- Glue things that are load-bearing, like landing gear struts
I typically tend to prefer working with medium-viscosity CA, but I’ll also use ultra-thin on one end, and Loctite’s gel-like CA on the other.
To apply CA, I typically pour some into a bottlecap (Topo Chico FTW), then use a toothpick or old airbrush needle to apply. When I’m working with thin CA and need to deliver just a small amount to an area, say biplane rigging or aircraft aerial wires, I’ll whip out Uschi Van Der Rosten’s CA-ndle applicator tips.
I rarely use CA accelerator. When I do, I’ve found great success using the Touch-n-Flow for very targeted application. For instance, when rigging up an aerial wire on an aircraft, I’ll position the wire how I need it, touch it with the CA-ndle applicator to apply CA, and then drip a single drop of accelerator on top. So much cleaner than the traditonal pump spray.
Sometimes, super glue is overkill, or just not the right choice. When I’m gluing fairly delicate bits, or clear parts, I prefer to use PVA glue. This is white glue, or acrylic glue. Call it what you will. It’s all more or less similar.
My favorite PVA glue, hands down? Gator’s Grip. It’s got a surprisingly tenacious bond and is exceptionally resilient to sheering forces. Up above I talked about using CA for items under tensile (pulling) stress. Well, CA is exceptionally brittle, and so it tends to succumb to sheering (sideways) forces. That mass balancer or antenna? Knock it the wrong way and suddenly you’re on your hands and knees trying to find where the damn thing went off to.
With Gator’s Grip (and to a lesser extent the more widely available Micro Kristal Klear), you get ridiculous resistance to sheering. Hit that antenna, and it’ll go sideways, but fixing it is just a matter of tweaking it back to where it was.
As a caveat to that…PVA glue is terrible for anything that will be under tensile stress. It’s relative elasticity means that that pulling force will literally pull it free. So yeah. Don’t use PVA for biplane rigging or anything.
Every now and then, I really have to just glue the hell out of something. The landing gear struts on HK’s 1/32 B-25. That kind of thing. I need the strength of CA, but the extra time to get everything aligned.
When that need strikes, I reach for my 15-minute epoxy. It’s a pain in the ass to use. It’s goopy and stringy and smells awful. But it does its job.
Check out what others are using
It seems to me that every modeler uses a slightly different combination of glues to get from a box of parts to a finished model. Here’s the rundown of what others in the Sprue Cutter’s Union are using to make things stick to other things.
6 Comments Add yours
Yep, hope they never stop producing M.E.K. !!!
Yep, hope they never stop producing M.E.K. !!!!!
Very good article with some helpful tips. As a chemist, I would like to point out that Tenax 7R is actually not MEK, but methylene chloride aka dichloromethane, a probable human carcinogen which is handled with great care, only in fume hoods, in labs. I would never touch it. Tamiya extra thin lists its ingredients on its label – harmless in comparison (acetone and am ester).
Wait, I thought viscous meant “thick” and resistant to flow. Honey would be highly viscous. Tenax seems quite thin to me, which means it is not viscous, but mobile. Do I have that backwards?
You are completely correct – I’ll edit to correct. The perils of a history major wading into fluid dynamics…
Good article ; Best concise breakdown of the various types I have seen.