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How to Do Urethane Casting on a Model Railroad

Plenty of hobby stores sell scenery pieces for model railroads, but a large part of the hobby still comes down to what you can make yourself. This is especially true when it comes to terrain. Train hobbyists usually make their own using molds that they either make themselves or purchase from the craft store. Although hobbyists often use plaster with these molds, a plastic urethane resin is ideal because it creates a very lightweight, detailed replica.

Things You'll Need

Plastic sheet
Face mask or respirator
Gloves
Silicone terrain mold
Urethane resin kit
Plastic cups
Mixing stick
Primer
Acrylic model paint

Instructions

- 1
  Lay a plastic sheet, such as a tarp or plastic wrap, across your work area to protect the surface from potential spills. Use a work area that is well-ventilated and not easily accessed by pets or children. Don a dust mask or respirator and a pair of gloves.
- 2
  Place your silicone mold upside down on top of the plastic sheeting. Open your resin kit and remove the two bottles within. These bottles are labeled A and B and contain two different liquids that, when mixed together, will cure into a hard resin.
- 3
  Pour liquid from the bottles into two different plastic cups, enough to potentially fill your mold. Usually urethane kits have a 1:1 ratio between the two liquids, so you should measure out equal amounts of each. However, check your kit's instructions to be sure. If a different ratio is recommended, follow that instead.
- 4
  Pour the contents of both cups together into a third cup. Stir the contents with a mixing stick for one full minute. Try to eliminate any bubbles with the stick.
- 5
  Pour the mixture slowly into the silicone mold. If you see any bubbles in the resin, use your stick again to eliminate them. Also use the stick to guide the mixture into any deep crevasses in the mold that the resin might not otherwise seep into.
- 6
  Allow the resin to cure (harden). How long this takes depends on the resin you are using. Some cure within a few hours, others take a day or two. Consult the kit's instructions for an accurate estimate.
- 7
  Peel the silicone mold away from the resin terrain. Your terrain is now ready for your railroad set. You can paint it using modeling primer and acrylic paints used for painting miniatures, both of which are widely available from hobby stores.

Model Railroads