PROCESS

I molded and casted my index fingers! I made the first finger in class, following instructions from Dr. Wettergreen and the TAs: I began by creating the alginate mixture by mixing alginate and water in a 1:4 ratio in a silicone cup, then placed my finger in it and waited approximately 15 minutes for it to set. I slid my finger out, then made a plaster of paris and water slurry with a 2:1 by volume ratio. I taped a screw to the cup and left it overnight, and the resulting finger came out very smoothly (right one below)!

A few days later, I recreated the process, this time placing both index fingers in the cup, to mold and cast two fingers at once. The slurry had been thicker in this run through, and this made the fingers dry faster, but left them with excess material at the base and more air bubbles (left and center fingers above). I sanded the fingers, then coated them with black spray paint and a glossy finish. Here are the final results:

CHALLENGES

Overall, this process was quick and fun and there weren’t too many challenges beyond it being very messy. It was difficult to get the ratios right and mix the powders and water together well, both of which introduce variability in the process.

COST

• Labor:
  • $20/hour at 1.5 hours – $30
•  Materials:
  • Alginate – $3
  • Plaster of paris – $5
  • Black and clear spray paint – $10

Total – $48

I used an upper estimate for the cost of alginate and plaster of paris, performing a cost analysis with just enough material for molding the three fingers, but if the materials are bought in bulk, the cost would be significantly reduced. Overall, this is a fairly inexpensive and fast method to mold and cast.