Scratchbuild Cast in Metal

I intended to make metal casts of the spaceship miniature I sculpted, before the Thanksgiving holiday.  Due to the cold however the RTV rubber I used for the mold was slow to cure.  I returned from an out-of-town holiday trip to find the rubber finally cured.  Lesson learned there: use a 34W or stronger bulb and a container (plastic coffee jug maybe) to trap the heat around the curing mold, speeding up the process.

I pulled the master out of the rubber mold and brushed graphite into the cavities, like I normally do.   I poured a few test casts after heating up the metal, and found the mold wouldn't fill.  I'd heard of this before, but this was the first time I'd experienced it in my home drop-casts.  All of my previous spaceship miniatures had minimal protrusions that might create potential air pockets, but this design differed.  The large dorsal pods created ample opportunity for air to get trapped.  A few deep cuts in the mold and viola, a finished and easy cast.

As the picture above shows, my process creates pretty rough edges, even with a lot of razor blade and metal file clean-up.  Still, I like these designs as they have lots of variation and little lines to catch the paint and ink.  And there's nothing like fielding miniatures that you made by your own hand.

The picture below shows the life cycle of this miniature, from cradle to gaming table.  The object on the top left is the first master, made of spaghetti and scrap polystyrene.  I press the first master into blocks of polymer clay and then detail the resulting impressions.  The detailed impressions get filled with water-putty and the two resulting halves are joined to form the second master.  The second master is the middle sculpt and was partially destroyed during the demolding process.  I make a mold of this second master and then use the mold for metal castings.  The metal castings are the ships that eventually get painted.

Mold with air paths

Teaser for other websites