With the life cast being a success, the next step was to make a junk cast.
The purpose of this initial cast was to correct any imperfections and address any potential locking points. Because this is only a temporary cast, we used a softer white gypsum cement called Hydrocal.
The first step was to reassemble the silicone mold and mold jacket.
Once fitted back together, we used mold straps to keep the shell snug. We then sealed the nostril holes with a small amount of water based clay (WED Clay).
To keep the mold supported while we poured the plaster, we placed it upside down in a 5 gallon bucket.
Next, we mixed up some Hydrocal.
First warm water was added to a 5 gallon bucket. To guesstimate the volume, we expected the batch to double when the plaster was added. We started with about 4 inches of water and in the end it yielded about 8 inches of mixed plaster. (very offical unit of measurement, we assure you!)
Using a cup, the powder was sifted evenly over the top of the water. This continued until the surface resembled a “dry riverbed”. We waited for the water to absorb completely into the plaster then, using a whisk, mixed it all together.
The plaster was then slowly poured down the inside wall of the mold.
At about half full, we stopped pouring the plaster and rotated the mold to ensure coverage and avoid any air bubbles. Once evenly coated, the remaining plaster was poured into the mold. To further prevent air bubbles, we tapped it on the floor and, using our hand, felt around the nose and ears of the mold.
Since the plaster requires heat and moisture to fully cure, the mold was then covered with plastic.
In a couple hours the plaster was cool to the touch and was ready to de-mold!
As you can see, there are some bubbles that were captured in the silicone lifecast. You can also see the plastic wrap “bald cap” in all its glory! The next step will be to rasp off imperfections and add clay to the cast to make it perfect. It will then be ready to re-mold in Smooth-On Rebound 25 silicone.