For this assignment, I used molding and casting techniques to create a set of two of my fingers. I find them a bit creepy, so I won’t be hanging them up in my apartment. But now I have an idea if I ever want to give someone a weird gift.
The first step was making a mold using a 2:1 alginate-to-water mix. The exact measurements weren’t super important—the main thing was making sure the mix wasn’t too watery (so it could still solidify) or too thick (so it wasn’t impossible to work with). I mixed it in a cup big enough to fit my hand, stirred with a popsicle stick until most of the clumps dissolved, and stuck my fingers in. After about five minutes, I gently wiggled my fingers out. The gel still felt a little wet, so I was worried the shape wouldn’t hold, but I had the right ratio of ingredients and waited the right amount of time, so I trusted the process. Sure enough, I saw two little holes in the alginate!
Note: This picture was taken post-plaster—I’m including it here to show how the holes look after holding your fingers in the alginate mix.
Now it was time to make the cast using a 1:1 mix of plaster of Paris and water. I didn’t need as much volume this time since I was just filling the finger-shaped holes. I mixed for about 30 seconds until it looked mostly smooth, then poured the plaster in, making sure to fill the fingers completely and go just slightly past them. I was surprised by how thick the mix was—I had expected it to be more liquidy. Once filled, I left it outside overnight. This gave the plaster time to harden while also helping to prevent mold growth. Apparently, alginate is great at growing mold.
I thought getting the plaster fingers out would be as easy as wiggling out my real fingers, but I quickly realized it was way harder. Just trying to grip and pull the plaster out caused the tops of the fingers to break off. So, I switched tactics. Instead of just wiggling left and right, I also pressed on the sides of the mold to introduce some air pockets. That helped, and after combining it with more careful wiggling, I was able to get the fingers out without any major breaks!
One of the fingers wasn’t completely sealed and showed the nail on the inside, so I decided to try again. This time, I held my fingers a little straighter to make them easier to remove and to prevent the screw from sticking out. I also let the mold sit for two days instead of one to give it more time to harden. Since it was cold outside, I left it inside this time, figuring the lack of airflow might slow down the solidification process. When I came back after two days, the cast was much easier to remove—probably because it had hardened more. The top bits didn’t break off either, which was nice. Once I got them out, I let them dry for a bit, then rasped off the edges so they were rounder and looked more finished.
After that, I painted them gold, let them dry for about 25 minutes, then added a coat of clear paint to seal them. And just like that, my creepy fingers were done!
Cost Analysis
The total cost for producing two sets of fingers was $21.16. This makes molding and casting with alginate, water, and plaster of Paris a cost-effective manufacturing technique!
