Group Memebers
This week we worked as a group to create a couple of silicone molds, and cast other materials in the molds.
Molding
For the silicone mold, we used mold star 16, a fast curing 2-part silicone molding material. It has a mix ratio of 1:1, making it very easy to measure.
To measure the volume, we poured one half into each of two cups, and visually compared the levels to make sure it was as close as possible to a 1:1 volume ratio.
Next, we poured the two solutions into a third cup, and scraped the sides of the first two cups a similar amount. Once it was all in one cup we stirred it quickly and thoroughly.
With the solution prepared and starting to set, we poured it into a couple of wax molds to cure.
Once the silicone had cured, we took it out of the wax block using a screwdriver for leverage.
Casting
Finally we poured a 2-part plastic casting material into the molds using the same methods as we used for the silicone, and let it set.
The casts set fully, and were appropriately hard. The plastic formed a meniscus at the edge of the mold, and some bubbles formed in the mold and clung to the meniscus. When hardened this resulted in a ridge with some bubble cavities in it on the bottom of the cast. Sanding away the meniscus is enough to remove the bubble cavities as well. Because of this, I don’t think that degassing will make the process easier, because you might want to sand away the meniscus anyway, as it would also be difficult to prevent.
