RTV Silicone Mold Making & Resin Casting

Intent:

The following process is intended to demonstrate the mold making process for using an RTV [room temperature vulcanizing] silicone mold material. It is not my intention to promote recasting, or the notion of copying someone else's work. For the trooper, the fabrication of an authentic E-11 blaster replica requires some hard to find and expensive vintage military issue parts. Making a resin replica of an expensive part for your own purposes is the intent of this video. Losing an original part at a trooper event will really spoil your day. A lost resin replica is not as bad.

Mold Material:

I use Polytek Plasil 71-20. This material is available from http://www.bare-metal.com . This RTV silicone is easy to mix, and pour. It will only stick to itself, can be recycled by grating is with a cheese grater and used as a filler. 71-20 has no odor, and had a cure time of about 4 hours. The down side: the material is expensive. To learn more on mold making, see this video:

RTV Silicone Video [2.9mb mov] - Using Plasil 71-20

Casting Resin:

To make a resin casting of the molds we just made, I use Synair's Pour-a-Kast Mk I. This material is available from http://www.bare-metal.com . This is a polyurethane resin. It a 2 part liquid resin, and has a 1:1 mix ratio for easy measuring. Cure time is about 5 minutes. Demold time is about 10 minutes. Pour-a-Kast has a slightly sweet odor when curing but is not offensive. The hardened resin is very strong, can be machined, and is very easy to sand and work with. And when used with the 71-20 RTV mold material, requires no mold release agent. The down side is the material is expensive, but if purchased in larger quantities is not too bad. For more info on making a part from the RTV molds using the Pour-a-Kast liquid resin, see this video:

Resin Casting Video [4.8mb mov] - Using Pour-a-Kast MK I

 

For info on the vacuum forming videos click here.

For info on the MDF mold making videos click here.