How to use Hot Stuff CA glue for white-metal and resin small scale models


Share |

by Wayne E. Moyer

I’d been building models all my life, but when the first 1/43 scale white-metal kits were introduced in the early 1970’s I discovered a problem- the glues I’d used to build hardwood, balsa, and plastic kits simply wouldn’t work on metal. My first solution, 5-minute epoxy, wasn’t satisfactory for several reasons. First, it took five minutes to set up. And it was messy; excess glue squeezed out between parts and “strings” were left when applying it. And most importantly, the thickness of the glue layer left a noticeable gap between the parts of a very small model. Fortunately, a local hobby shop owner showed me something new, an alpha cyanacrylate (“super glue”, "CA glue") called Hot Stuff that came in several viscosities, left virtually no visible glue layer between parts, and depending on the viscosity, set up in anywhere from 20 seconds to a minute. When limited-run resin kits were introduced a few years later the same techniques I’d developed for white-metal kits, with a few small variations, applied to them, too. I’ve been using Hot Stuff now for almost 40 years.

I quickly learned two things (OK, 3):

1) The glue-to-metal (and resin) bond is stronger than the paint-to-metal bond so it’s best to build as many sub-assemblies as possible before priming the parts, and

2) You want to use as little glue as possible- - the more you use, the longer it takes to set and the bond may not be as strong. A very thin film of glue is what you want.

Oh, and that third thing? Hot Stuff sticks to human skin better than anything else so it’s nice to have a bottle of debonder on hand. That may leave you with a mess to clean up before re-applying the part, but it’s better than wearing a 1/43 scale brake rotor for several days until your skin finally sheds!

Photo 1

Since the early 1970’s I’ve built literally hundreds of white-metal amd resin models with the adhesives and applicators shown in Photo 1. About 90% of the time I use the medium Hot Stuff, “Super T” because I can control the amount used more easily. The thin Hot Stuff comes in handy where I’ve already tacked the parts together, or am able to hold them together, and want to use capillary action to run glue along a long joint; we’ll see that when building a resin airplane. Glue will build up inside and at the tip of the applicator and rather than keep opening up or cutting off the tip I use a “glue tip” that fits over the Hot Stuff bottle (front left).

Photo 2

For many years I used a round toothpick with one end cut to a sharp point and the other to a flat chisel point (Photo 2) to apply very small amounts of glue. I put a drop of Hot Stuff on a piece of glass, dipped the appropriate end of the toothpick into the glue, and transferred that to a hole (pointed end) or flat surface (chisel end). But the glue builds up quickly and just when you need a very small drop of glue the pointed end has a big glob of dried (OK, cured) glue and you’ve got to stop and either sharpen the point or make a new tool. I finally made some applicators from several diameters of brass wire with one end filed either to a sharp or chisel point and the other set into a piece of dowel. When glue starts to build up, a quick swipe over a piece of 200-grit sandpaper gives me a pristine surface. An unexpected benefit was that the thickness of the dowel keeps the pointed end from touching your work surface and instantly attaching itself thereto.

So let’s see how I use Hot Stuff and these simple tools to build models. We’ll start with a 1/43 scale white-metal car kit.

Photo 3

Tiny drops of medium “Super T” can be applied to one side of a two-part assembly like this engine/transaxle (Photo 3) and spread with the chisel tip,

Photo 4

or simply applied with the flat side of the chisel itself (Photo 4).

Photo 5

The airbox of this 1976 Formula One Parnelli was a good tight fit, so I used a long applicator tip to apply a thin bead of thin Hot Stuff to the inside of the joint (Photo 5). Capillary action will draw the thin glue into the joint and if you’re careful not to use too much, it will set up without going all the way through and leaving glue on the outside.

Photo 6

Super T is especially useful for gluing photo-etched wing endplates to metal wings (Photo 6). The endplates have an etched recess into which the end of the wing fits; I apply a small amount of Super T with the chisel point and then spread it to a thin film with the flat surface. Once again the 60-second (or thereabouts) cure time allows me to adjust the angle if that’s necessary. Super T’s gap-filling properties are also very useful.

Photo 7

After gluing the front wing to the nose cone (Photo 7)

Photo 8

I ran a small bead of Super T along the join line (Photo 8) and gave that a quick squirt of accelerator.

Photo 9

I used a modeling file (Photo 9) and sandpaper to remove the excess glue before priming the parts; the sanded Super T is as smooth and non-porous as the surrounding metal.

Photo 10

Photo 10 shows several of the completed subassemblies before they were primed and painted.

Photo 11

Photo 12

The different size “needles” allow me to apply appropriately sized drops of Hot Stuff (Photos 11 and 12) as needed.

Photo 13

They’re especially useful when it’s necessary to apply a drop of Hot Stuff into a hole (Photo 13) without getting glue on the surrounding surface. That works especially well when assembling multi-piece wheels like those shown here. The center-lock lug is a pin that fits into a hole in the axle; a thin pointed tool can be used to apply glue just to the inside of the hole without getting glue on the pin itself.

Photo 14

If the parts must be primed and painted before assembly, the glue joint will be stronger if paint is scraped off (Photo 14) before the glue is applied.

Photo 15


Photo 16


Sometimes a glue joint will come apart while handling one of these small models, especially if the glue was applied after the part was painted. A small drop of Hot Stuff Super T can be applied exactly where it’s needed (Photo 15) and I’ve found that instead of spraying accelerator over the whole area, it’s better to squirt some onto an X-Acto knife blade and use that to apply a pinpoint drop of accelerator just to the mended joint (Photo 16).

Photo 17

Details like photo-etched hood straps on older race cars are easy to apply neatly with Super T, too. Simply glue one end in place, let it cure, and then form the strap to shape. A small amount of Hot Stuff is then wiped onto the inside of the strap (Photo 17) and it is pressed into place for a few seconds.

When resin airplane kits were introduced in the early 1980’s, they presented the same problems, but of course I already had the answer: Hot Stuff. The techniques are pretty much the same as used to build low-run injection-molded plastic kits; you just use Hot Stuff instead of thin liquid plastic cement.

Photo 18

Like those low-run plastic kits, there are rarely any locating pins so once the parts are ready for assembly I apply a thin film of Super T to a mating surface at one end of the fuselage (Photo 18), carefully align the pieces, and hold them for a minute while the glue cures. If you’re careful, everything will be lined up but if not, gluing just one small spot will allow you to tweak things a bit to get it right.

Photo 19

I then tape the front end together and put a small drop of thin Hot Stuff in the seam (Photo 19) and hold it together for 30 seconds. If there’s an opening that will allow you to apply glue from inside the fuselage, by all means do that. If you’ve used too much Hot Stuff and it squeezes out of the seam, or you’ve missed the seam, wet-sand the excess CA glue right away with 240 and 400 grit paper. The glue is relatively soft for a while; once it’s fully cured the glue is harder than resin and difficult to sand without damaging the model.

Photo 20

This model (Mr. Mulligan) needed a long-range fuel tank that wasn’t included, so I made one from two pieces of balsa covered with 0.010 sheet plastic (Photo 20). All held together with Super T. of course. The last step in the interior was to glue the fragile resin control columns in place.

Photo 21

Here again the pointed tool let me place a small drop of Super T (Photo 21) just in each hole before setting the sticks in place.

Photo 22

One-piece wings can simply be held in place (Photo 22) while a bead of Super T is applied along the seam; the 1-minute (or thereabouts) cure time allows you to make any adjustments needed. When one side is set, the other is done the same way.

Photo 23

This kit (Dekno’s Mr. Mulligan) was very unusual in having slots and tabs for the tail surfaces, which made gluing them in place (Photo 23) a snap. Most resin kits (and low-run plastic kits too) simply use a butt joint for the wings and tail surfaces. Not even Super T is strong enough to be confident that a really thin butt joint won’t come loose during handling.

Photo 24

My solution is to make “stub spars” by drilling the largest possible hole (Photo 24) in the root end of the flying surface (wing or tail).

Photo 25

Photo 26

A piece of brass wire is glued into the hole (more Super T of course), cut off (Photo 25), and used to mark the location on the fuselage root (Photo 26). A larger hole (allows me to move the surface if needed) is drilled in that root, a drop of Super T is put into the hole and along the root, and the surface is held in place. Once again, Super T’s cure time allows me to make any necessary adjustments to location or dihedral if necessary. Two-piece wings are done the same way, just using larger brass rod. I use this system, with Super T, on low-run plastic models too, and haven’t had a tail surface come loose yet.

Photo 27

Don’t forget to sand the seam as quickly as possible in case any glue is squeezed out. If you’ve sanded the parts to get a good fit first, you’ll rarely need any putty to fill the seams (Photo 27).

Photo 28

Photo 29

Landing gear, antenna masts, struts and braces, and other small details can be added easily and quickly with Hot Stuff. You’ll find many more uses for Hot stuff when building small-scale models; just remember, the less you use, the better. I’ve built well over 500 1/200, 1/72, and 1/43 scale resin and white-metal models in the last 40 years (Photos 28 and 29), and every one of them was built with Hot Stuff. There are lots of other CA glues now, but when you’ve got something that works right, every time, why change?

About Wayne Moyer

Wayne graduated with a degree in AeroSpace Engineering from the University of Cincinnati in 1964 and began a 37-year career as an Aircraft Design Specialist in the Preliminary Design Group at Wright-Patterson Air Force Base. He began building balsa airplane models as soon as he was allowed to have a single-edged razor blade (X-Acto knives hadn’t been invented yet) and has never stopped.

The release of the first plastic kits started him building model cars as well as airplanes. He began collecting 1/43 scale diecast models in 1966 and wrote a story about modifying Dinky and Mebetoys Ford GT models to make them more accurate for Collector’s Automotive Replica Society (CARS) in ’68. That led to the purchase of one of John Day’s first white-metal kits, the Mercedes 300SLR, in the early 1970’s. A story about building that was published in Scale Modeler in 1972. John Day liked it and sent some more kits and, well, things just got out of hand. He’s written about model cars and airplanes in one or more magazines continuously since then and has had more than 2000 columns and articles published in magazines in this country, England, Japan, and Australia.

Wayne earned his private pilot license in 1969 and has been flying since then. His biggest “modeling project” has been the construction of an Experimental Van’s Aircraft RV-12 (sorry, no Hot Stuff used there) whose first flight was in the fall of 2010. Wayne and his wife Kay live in a suburb of Dayton, Ohio and have 4 daughters and 8 grandchildren, along with a variable number of cats.

Wayne in his Experimental Van’s Aircraft RV-12

Wayne E. Moyer
wmoyer@woh.rr.com