In this week’s project of molding and casting, I made a mold of my index finger and casted two plaster wall hooks out of it. In the first trial, I eyeballed the amount of alginate powder and water needed, mixed them until there weren’t big chunks, then inserted my index finger into the mixture until it started to harden. I then made the plaster mixture by slowly adding plaster powder into a cup of water until it was at the right consistency, then poured the plaster mixture into the alginate mold. I waited around 2 hours until I tried to pull the dried plaster out, however the finger broke as I was pulling it out. I then had to tear the alginate mold to get the rest of the finger out, which was still a little damp so I left it out to dry.
Broken finger cast when pulling out of the alginate mold in the first trial
I later made two additional alginate molds, this time I followed the given weight ratio between the alginate powder and water, 1:4. I used the same method of making the plaster mixture and casted both of the molds I made. I waited for the plaster to dry for another 2 hours, both of the fingers were able to slide out easily and I left them out to dry for a day as they were still wet. I then dried the alginate molds with a paper towel and then poured more plaster mixture into both of the molds. This time only one of the fingers was able to slide out of the alginate mold, the other one broke so I had to cut the alginate mold to remove the finger. I left them all out to dry and it ended up super cool as I could see my fingerprints on the casted fingers.
Left: Plaster cast drying in alginate mold and a screw suspended with tape. Right: Creating an alginate mold of my index finger
Dried plaster cast of my index finger (the mold it was casted in in the background).
Trial 2 successful casts
Cost Analysis:
Alginate:I used around 70grams of alginate per mold, which totals up to 210 grams of alginate per mold. At $0.02/gram, the total cost for the amount of alginate used is approximately $4.2.
Plaster: I used around 150 grams of plaster of paris, at $0.007/gram, the total cost for the amount of plaster used is approximately $1.05.
Screws:I used a total of 5 screws in this project. At $11.99 for a box of 100 drywall screws, a single screw costs approximately $0.12, the total cost for the screws used is approximately $0.6.
The total cost for making these finger molds and casts is $5.85.
