how do you cast structures

[dehusman]

I assume you will be making thin flat castings. I would suggest using a silicone RTV rubber. Alumilite or Smooth-on are two manufacturers. Check with them to see if they have one designed for use with plaster. Build a dam around your mold, at least 1/2 in taller than the highest spot on your master. Legos, wood lathe or plastic strips work well. Make sure the surface the master is sitting on is level and pour the RTV over the master. It will seek a level surface. Otherwise overfill the dam and place a piece of flat styrene or glass WELL covered with release on the the top of the dame to get a flat back.

If you just use a brush on latex mold making material it will be difficult to get flat castings.

Use a dense plaster such as Hydrocal or a dental plaster to cast the wall sections.

One way to do the windows is to make the walls extra thick and put the windows in the master walls, then put a piece of plasticbehind the window. When you cast the walls the windows will be cast integral with the walls, but the windows won't be "open". You will have to paint the "glass" parts black and cover with a gloss coat to look like glass.

Dave H.

[Anonymous]

I was wanting to build a city scene and wanted to cast structures in either resin or hydrocal. I have the master made, and it is designed to interlock both horizontally and vertically. I have seen latex type stuff to make the mold with and I was wondering would plaster be too fragile? can you cast the windows or do you have to buy them for every window in the casting. I would like to avoid buying thousands of window castings if I can. I know that it has been done by others. please let me in on the secrets. thanks