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Resin-casting/Reproducing parts

Q-1: I have a question about resin casting. How do you go about creating a master to cast from when there are no existing kits to base it on?

Most often, beginners like me use an existing kit body to duplicate. I am interested in producing new material that's not currently available.

I am sure that given this information, a lot more subjects would be available from other hobbyists.

- Adam Schroeder
Acworth, Georgia

Q-2: I've created a custom car body that I think turned out pretty good. I'd like to duplicate it, but have never tried casting with resin. How could I make a mold and cast several copies that I might even be able to sell to cover my expenses?

- George Falkin
Kitty Hawk, North Carolina

Ken: Adam, creating a master to reproduce, be it a single part or a full car body, simply requires building the piece just as you would if you weren't going to duplicate it. Remember, what you build is exactly what you'll get if you properly create both the mold and the casting.

In your case, the key is to successfully create your body of choice to the point where you're satisfied that it's flawless, then create the mold.

George, it appears that you have the building angle down pat, but there are cold, hard issues at work here that amateur resin casters must consider:

The high quality of aftermarket resin bodies currently available has made a complicated casting process look too easy! Before attempting to reproduce an entire body, I'd suggest that you get your feet wet with simpler molding and casting projects that will familiarize you with the medium.

Entire articles could be - and have been - written about making molds and casting parts, so any advice we offer here will merely scratch the surface; however, in this limited space we can provide an overview that will hopefully point you in the right direction.

And before we go any farther, you must consider the problems of reproducing copyrighted material. Anything you make for resale must be of your own design - not just a repop of someone else's kit part - or you can get into some serious legal trouble for copying someone else's work.

Check out the Car Modeler article that's referenced a little later in Ken's answer for a good summary of the issues invovled here.
- Jim Haught

Let's start by making a simple, one-piece mold.

The process of reproducing a part begins with an original or "master" part. Using that master, a flexible mold is created by securing the part within a dam, coating the master with a release agent (so the mold material doesn't stick to the original), mixing the mold material, and pouring it over the part. Care must be taken to avoid air bubbles in the mixing and pouring procedures.

When the mold has cured, remove it from the dam, and carefully pry out the master. You now have an exact "negative" of the master in the mold.

Now you're ready to cast the duplicate part. Mix up the casting material, be it resin, plaster, or whatever other material you decide to use. Coat the inside of the mold with a suitable mold-release (Note: That's why resin parts need to be thoroughly washed when you get them - to remove any trace of release agent that will affect the painting procedure). Slowly pour the casting material into the mold, being careful to avoid air bubbles.

When the material has hardened per the manufacturer's specifications, remove the part, and you're ready to make another one. Of course, there are tricks and techniques that will come with experience, but that's the basic procedure.

With all this information in hand, Micro-Mark has great starter kits for aspiring and seasoned resin casters. Check out their products on the Web at

As far as some other useful information on the art of resin casting, Car Modeler 2002 has a terrific article by current FineScale Modeler Editor Matthew Usher about creating one- and two-part molds. Matthew's article also covers some basic casting techniques that you'll find quite helpful.

Car Modeler 2002 is still available as a "back issue" from Kalmbach. Check out the Scale Auto Web site:

Good luck with your projects, gentlemen, and thanks for the thought-provoking questions.


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