Molding and Casting

Horse Drawn Hearse Ornament

For my Halloween display this year I'm building a horse drawn hearse replica.  One of the details I wanted to reproduce is the metal filigree ornament as seen in this picture of the Haunted Mansion hearse at Disneyland.

I found an authentic ornament on ebay, and successfully bid on it.  The problem was that I needed six of these for my hearse, and it would be virtually impossible to find matching ornaments.  I decided to make a mold and cast replicas.  I found this company, Synair, a manufacturer of molding and casting materials, and ordered a goodly amount of their Por-a-mold mold making urethane RTV rubber and Por-a-kast urethane casting resin.

I prepared the ornament, the master, for mold making by placing it in a shallow clay filled pan.  The master had to be slightly sunk into the clay so that when the liquid rubber is poured on to it, the rubber wouldn't seep behind the master.  I found that a q-tip dabbed in Noxema allowed me to eliminate any gaps between the master and the clay.

Once I was satisfied with the clay and master, I put little dams into the clay.  This is so I could use less of the rubber for the mold.  I sealed the edges of the dams with clay so the rubber wouldn't seep through.  I then sprayed a coat of the Synlube 531 spray on release agent.  This is a very important step.  With out this the finished mold would be stuck to the master forever.  

I followed the directions that came with Por-a-mold and mixed a batch.  I then poured it over the master.  

I then clamped a jigsaw with the blade removed to the table and turned it on.  The vibration from the saw caused the air bubbles in the mold material to rise to the surface.  After waiting 24 hours I removed the mold from the master and prepared it for casting.   After spraying the mold with a coating of Synlube 531, I poured Por-a-Kast into the mold.

This picture shows a replica on the left and the original ornament on the right.

This is how the replica looks right out of the mold.  It still needs to be cleaned, have the excess resin removed and painted.

Comments? Complaints? the_boss@restin-petes.com