Moulage en Résine

1/72 Scale Modelling Techniques

Commercial véhicule parts cast in resin

If you have not tried resin casting yet, by all means do. It is not beyond the ability of any experienced modéliste et will open up a world of possibilities. You may pick any subject you choose for a first attempt, but you will be more successful if you choose something that will work in a one-piece mold. Any object avec one flat side, i.e. avec no detail on that side, will work. Starting this way, you will not have to be concerned avec "gates" et "runners", the channels that carry the resin into the actual mold cavity et allow air to exit. Get some experience before you tackle gates et runners. Also, if you decide to use GE 3110 RTV resin, you should pick a master that does not have very deep undercuts as this material is not flexible enough to allow extraction of your master if it has more than moderate undercuts.

Tools et Materials

  • Alumilite resin
  • CASTALL RTV
  • GE 3110 RTV
  • 4″ × 4″ Flat Glass
  • 1 mm Sheet Styrene
  • Modelling Clay
  • Hot Glue
  • Vaseline
  • Mineral Spirits
  • Disposable Brush
  • Baby Powder

Casting Materials

The techniques described in this article may be used in conjunction avec various resin casting materials available on the market today. The author recommends CASTALL RTV, GE 3110 RTV et Alumilite resin, but any similar products should produce good results as well. If you are new to resin casting, do yourself a favor et contact manufacturers directly to obtain their literature on the subject. Alumilite Corp has a small et very informative booklet on the subject, which will point beginners in the right direction.

Alumilite resin
Alumilite Corporation
315 E. North St.
Kalamazoo, MI 49007
1-800-447-9344 Toll Free
1-616-342-1259 Fon
1-616-488-4001 Fax

Représentants de l'enterprise were very friendly et helpful to the author.

CASTALL RTV is an industrial product which you probably will not be able to purchase. Based on conversations et research may I suggest that beginners substitute GE 3110. This is available from many sources including Alumilite, who also have a quick cure catalyst that will cure the product in about 1-2 hours. I am also told that this RTV does not need to be de-aired. Though I have not experimented avec it yet, this is what I will try when my CASTALL runs out.

Preparing the Mold Box

I used a 4" X 4" piece of ordinary glass to build my mold on, because it is cheap, easy to obtain, easy to clean, et will not adversly affect the cure of RTV as wood might. Using just a tiny drop of white glue, glue your master in the center of the glass avec its flat side down. Now build a "mold box" around the master. I use pieces of .040" (1mm) thick styrene to build a box around the master. Allow at least 1/2" of space all around the master, including above it. You may use any type of glue on the box that you would like, but be sure that the mold does not leak, the RTV must be held in place around the master as it cures. Hot glue would work well for this et it is very quick. Use modelling clay ou hot glue to seal the box in place around the master. Reader suggestion: Dave Wachter recommends using LEGO blocks to build mold boxes of any shape ou size. The LEGO blocks seal perfectly, et they can be used again et again.

Pouring the Mold

Mix the RTV following the directions that came avec it. I can't emphasize this strongly enough. I am told by the experts that most problems stem from not thoroughly understanding the directions for the products used. When you pour the RTV, begin pouring directly over your master et pour very slowly. You are trying to avoid air bubbles on the surface of the master as these will render your mold useless. You may want to use a disposable acid brush to paint a coat of the RTV on the master to ensure that there are no bubbles on the surface. I did not find this to be necessary, but keep it in mind as a solution to the problem of bubbles.

I have found that no mold release agents are needed on the master. You may want to use it on the glass et the inside of the mold box to make removing the mold easier. I used a mold release made from petroleum jelly et mineral spirits. Mix a 1/8" diameter ball of Vaseline to a teaspoon of the paint thinner. Use a Q-Tip to apply this sparingly to the glass and inside of the mold box. Allow the RTV to cure for the time that the manufacturer specifies. When cured remove the mold box et remove the mold from the master. If you have trouble removing the mold from the master, soak it in warm water to break the white glue joint. Once the master is free from the glass, bend et flex the mold as needed to free your master from the mold.

Using the Mold

It is now time to pour a casting. Dust your mold cavity avec Johnson's baby powder et blow off any excess. This will help prevent any air bubbles at the surface of the cast part. If you use Alumilite resin you may want to refridgerate it for about 20 minutes to slow the cure et give you a little more working time as this stuff "kicks off" fast. No matter which resin you choose, it is very important to read, understand et follow the manufacturer's directions.

Using a disposable plastic mixing cup (available at your local hobbyshop) mix a batch of resin. Be sure you mix enough to fill your mold cavity. As soon as it is mixed, pour it into the mold. Pour slowly et start pouring into the deepest part of the cavity. Fill the mold slightly above the surface et then slide a piece of glass over the surface of the mold. This will ensure a flat bottom to your cast part. It will cause some flash, but this will be minor et is easily removed. The resin will cure in a matter of minutes. When cured, remove the cast part from the mold in the same way you removed your master.

Bill Rittner

Questions Fréquents

Pour plus d'informations, veuillez contacter les éditeurs de la revue Military Miniatures Magazine au Miniatures Forum.

Modélisme et Figurines