Can you tell me what Hydrocal is? What makes it different (better or worse) than plaster?
Also what is resin? I know you use it as a material to put into molds to dumplicate parts but what is it?
Also are these items available at places like Michaels?
Thanks,
Pete
Resin is a plastic material. I don’t use it, so I won’t go any further.
Hydrocal is a plaster, but it’s very lightweight. It sets up very quickly. I don’t know if Michaels carries it, but I get it from my LHS. I get the big 10-pound container. It makes very good rock or rock-wall castings. I like the texture, and the way it takes paint.
I haven’t seen it at Michaels either, so I by the Woodland Scenics brand at my LHS. It is excellent for making rock castings as it takes fine details very well. Be sure to use a release agent (a few drops of dishwashing detergent in a water works well) and shake the plaster before mixing. Otherwise the powder seperates and your castings will crumble apart. As for resin, I haven’t used it for casting, but I make rivers and streams with a product called Envirotex. It is a clear, two part resin that is extremely durable once set and can be dyed and poured in layers to represent depth. I have heard of it being used for casting parts as well, and it seems that it would work, as long as a proper relaease agent is used. (one downside to resins are the fumes, they can be strong and dangerous if used in a confined area)
Usually what is meant by resins these days is polyurethane, which sets solid in a variety of short times, depending on the particular compound chosen. It’s cast in rubber molds made from room temperature vulcanizing (RTV) rubbers. It yields excellent detail, and is a robust material.
Set times vary from about 90 seconds to 10 minutes or so, with demold times between 10 minutes and a few hours. It takes some practice to get used to.
For examples of the materials, try Alumilite at: http://www.alumilite.com/ and Smooth-On at: http://www.smooth-on.com
Years ago, polyester resins were used for making castings. One source was the Castolite Corporation. Polyester attacks the surface of RTV rubbers eventually, causing deterioration of the mold. That, and the fact that polyesters usually took a longer time to solidify, led to their being displaced by polyurethanes.
Both Alumilite and Smooth-On have introductory kits, with about a two pint quantity of urethane. Alumilite may be available in your local hobby store. Check the dealer/distributor button on their website. Smooth-On materials can be easily ordered direct from their website. Micro-Mark also sells one or two of Smooth-On’s products.
-Ed