PROCESS
The first step was to mix the alginate with water at a 1:1 ratio. We used the lines on the cups given to eyeball these measurements since we were told that they didn’t need to be perfectly precise, and the only effect of slight miss corrections would be the time for the mold to cure. We stirred the water/alginate mixture for about 3-4 minutes before Dr. Wettergreen gave me the OK to stick my finger into the cup. The mixture set in for around 8 minutes, once I felt like the mold had sufficiently solidified, I removed my finger.
After creating the mold, we started on our plaster mixture, which was created at a 2:1 ratio of plaster to water. We mixed this concoction for a few minutes and then poured it into the small opening of the mold. Once fully poured, we attached a screw to a piece of tape and inserted the screw into the plaster––the tape holding it afloat in the finger mold.
After the plaster dried, I was able to demold the finger from the plaster pretty easily, without having to break the mold. This allowed me to simply pour more plaster into the mold to create my second finger, instead of having to create a whole new mold.
(note the discoloration of the top finger, which was left in the mold for longer than the bottom one).
Now that I had the fingers demolded, I moved outside to finish the fingers with Smoke Gray spray paint, which also acts as a gloss protective layer.
As a final finishing touch, I also chose to paint the nails on the fingers, to add a little personality.
REFLECTION
One thing that I missed from the instructions was that the plaster releases water as it dries, so we weren’t supposed to not leave it overnight. I failed to do this, and this is a possible reason for the bubbles that formed at the base of the fingertips, and the odd color of the second finger when it was initially removed from the mold. There were some pretty major defects at the fingertips of both fingers, but especially on the second finger created. I noticed, however, that most of the errors were found on both fingers, which means that although imperfect, the product created was properly reproducible. I think that reusing the same mold caused the second finger to have additional defects, as well, given that the removal of the first finger may not have been perfect, or possibly there was left-over plaster in the mold from the first finger that detached, and thus would alter the inside volume that the second finger would fill.
I think that this process was pretty straightforward, but if I were to do it again, I would do a better job of creating a perfect mold at first, so that imperfections weren’t present in the subsequent fingers created. I also think that leaving the fingers in overnight didn’t help with the presence of imperfections in the fingers, so I will be more mindful of this when we work on the final project mold.
COST ANALYSIS
Raw Materials
- 1/2 lb of Alginate = ~$4.5
- 1/2 lb of Plaster = ~$1.6
- 1 cup of water = ~$0.01 (estimate)
- Spray paint = ~$0.05 (estimate)
Labor
- 2 hours = $30 ($15/hour)
Overhead
N/A
Total Cost = $36.16
This converts to a price of ~$18 per finger. In my opinion, that’s pretty steep, but in the future, I could cut the labor time in half by more efficiently timing different steps of the process. A further step would be to 3D print the fingers, and have those fingers be dipped into the alginate, which would eliminate any error from moving around in the mold, and would also allow for multiple molds to be created at the same time, in the same way.
