A Resin Model Kit Primer
A basic guide to building Small Art Works kits

If you are already familiar with making resin and composite model kits, you can ignore this article. However, if you are new to the hobby, and are only familiar with building the commercial injection molded styrene models that have been the mainstay for so many years, you may find some tips here that will help you to get the most out of your new kit from Small Art Works. Even if you've built some resin or composite kits before, read through this anyway, as you may discover some techniques that you hadn't thought of before.


The model kits available from Small Art Works and others like it are generally referred to as "Garage Kits". This term has been coined to represent the fringe of the model kit manufacturing community (generally individuals) who produce kits (yes, sometimes in their garage!) that number in dozens, rather than the hundreds or thousands or millions that constitute the bulk of consumer-oriented commercial model kits sold at regular retail outlets.

These Garage kits may, at first glance, seem terribly crude compared to the mainstream polystyrene kits you may be more familiar with. The reason for this is simple. Garage Kit manufacturers are rather low key and do not have a lot of money at their disposal for a multi million dollar machine shop to produce expensive steel molds (commercial kit molds can cost half a million dollars to produce) and the other high tech equipment and staff used to produce mass market kits on a very large scale. Instead, Garage Kit manufacturers use silicon rubber molds and urethane resin to produce the parts for the kits like the ones available here. This process allows for lower startup costs than the injection molded production runs the big companies use, but it also allows Garage Kit manufacturers to produce more specialized products with much smaller production runs that would be impractical for the mainstream companies. This is a good thing, because it allows the enthusiast to buy kits that would not normally be available if left up to the usual large manufacturers. Yes, the Garage Kits are rather expensive part-for-part when compared to the mass produced ones available at department stores, but that's the price paid for having a kit available that's more suitable for your particular interest. Also, Garage kits are more labour intensive on an individual basis, and the materials are more expensive per kit when compared to the mass-produced examples.


First, the model the kit is based on was extensively researched to the point where an accurate master pattern of the model could be made. This master pattern was built completely by hand, keeping in mind that the law of gravity and physics of fluids would play a part, and a rubber mold of this master would have to be made. The completed pattern was then covered in a silicone rubber compound, which begins as a thick gooey liquid that, when a catalyst is added, hardens around the master. After about a day, the flexible rubber mold was then removed from the pattern and casting of the resin copies were then made from urethane resin. Urethane resin is a two part liquid that, when combined, reacts to form a solid compound. The mold was prepared, then a quantity of resin was mixed and poured into the mold. Within a few minutes, the copy of the master becomes solid, and can be removed. The resulting pieces are the parts of the model that are made into a kit. All of this is done by hand, one piece at a time, making the production run fairly labour intensive and time consuming.

This process replicates very accurately the original master model down to the last detail, but the casting process usually introduces some flaws, such as air bubbles, "flash" and spillover along the mold separation lines or edges. Sometimes some excess resin has "heaped" at the top of the mold where it was poured.  You must sand this flash before the parts can be assembled into the final unit.


As a consumer, you will have to pay more attention to the preparation of the parts with a Garage Kit than you would an injection kit. There are flaws that you will have to fill, trim and sand before you begin the assembly of the kit. Trimming some of the "positive" bubbles, which look like small bumps on the surface, is easy. Usually they can be picked out with the end of a knife. To fill "negative" bubbles, you can use standard modeling or automotive putty, or you can use medium or thick grade cyanoacrylate, or "CA" (superglue) and a little accelerator. Cyanoacrylate is the "official" name given to what you would normally call superglue. First, using an eye dropper or similar tool, apply a bit of accelerator to the inside of the bubble, allow to dry then apply a drop of CA to fill the cavity, Then more accelerator if necessary. For some problem areas, you can apply the CA like this in layers to build up the surfaces. When hardened, the superglue sands pretty much like the resin the kit is made of. Use a small file to remove most of the material and then finish with fine sandpaper. If any resin parts are warped or bent, you can heat them with a hair dryer or hot water and slowly flex them back into the correct shape. Use patience and work slowly to avoid breaking the parts. If the parts break, they can be glued back together using the CA.


Assembly of the resin parts of a kit can be done using epoxy or the CA adhesive mentioned above. I recommend the better quality CA that can  be purchased at your local hobby shop, not the cheap and inferior super glues (such as the "Krazy Glue" type brands) available at department stores.  There are three different grades you should know about. The thick grade CA flows much like corn syrup, and can be used for areas where large gap filling is required and quick setting is not necessary.  The medium grade is the most useful. It fills tiny gaps and is just runny enough to use a bit of capillary action to inch into not-so-deep crevices. The thin grade (recommended for experienced modelers only) runs like water, and can actually be dangerous if you are not careful (never squeeze the bottle while looking into the spout, for example, or you will do some very serious damage to your eyes!). The thin CA will bond your skin instantly. Exercise EXTREME caution when using the thin grade! Use the thin CA by holding the parts to be joined together, and then apply a TINY amount of thin CA to the joint. Capillary action will carry the glue into the joint, forming a very solid bond. It is important that you make the parts match very closely. The thin CA will not fill any gaps. Also note thet thin CA is very runny like water, so caution must be used to prevent it from running into areas you don't want it to. Keep a dry rag and CA debonder handy to wipe away any spills.

Recently I became aware of an excellent CA glue called Gorilla Glue, a superglue that is very strong and commonly available in most hardware stores. Unlike most department store superglues, Gorilla Glue is very high quality.

You will also find the use of CA accelerator (also available at your hobby dealer) very useful. Sometimes when a joint is stubborn and will not seem to bond, you can force the glue to cure instantly by giving it a shot of accelerator. This also helps in gap filling. 


The use of accelerator will cause the glue to cure VERY quickly, and a lot of heat is generated from the chemical reaction. Sometimes, if you have a relatively large quantity of glue pooled in a deep cavity, the glue will often fizz, sizzle, spit, pop and smoke when the accelerator hits it, so you should wear eye protection. The escaping fumes can also be exceptionally irritating, so keep away from them. Provide yourself with adequate ventilation and fresh air. Also, if you have any of the glue on your skin which is hit by the accelerator, it will cause very nasty burns (especially with the thin CA).  Always exercise caution when using CA and accelerator to avoid some very unpleasant experiences! Remember, we want model building to be FUN!


Finishing and painting a resin model is just like the styrene kits, with one major exception. The resin your kit is made from will take most types of enamels and acrylic paints such as all hobby paints, spray paints and even automotive lacquers (which damage styrene kits) quite nicely! But hobby paints designed for plastic model kits still work best. Use the standard preparation techniques for all models, like washing the parts to eliminate greasy fingerprints and mold release agents. I also recommend priming all the parts before painting with an cellulose or lacquer based primer, like automotive primer. This also helps you locate minute flaws before finishing. Spraying with an airbrush is preferred, but you can use spray cans and hand brushing too.


The assembly and preparation techniques of urethane resin kits may seem very difficult to you initially, but in reality, once you understand the construction techniques and nuances of working with resin, you may find them just as easy as the "regular" styrene kits!
Jim Small,     Small Art Works,      jim@smallartworks.ca