For this assignment, we were tasked to create a mold of one of our fingers using alginate and cast it using cement. To begin the process, I first added 3 parts water to 2 parts alginate. I used 9 oz. of water and 6 oz. of alginate.
I then combined the two, stirred the mixture, stuck my index finger in it, and waited until it hardened.
I then pulled it out. My first mold turned out pretty cleanly.
I used Quikrete to cast my first finger. The instructions said to use 5 parts cement and 1 part water, so I added 1 oz. of water to 5 oz. cement and ended up creating a lot of extra cement.
I mixed the cement and water together but the cement was super thick. This made it very difficult for me to cleanly pour the concrete into the my mold.
I also forgot to put the screw in until later, and I ended up trying to put it in as the concrete was hardening which probably disturbed the process.
The instructions stated to wait 10 – 20 minutes for the concrete to harden, however, after waiting 30 minutes it was clear that the cement was nowhere near dry. I tried to cut the alginate and get the finger out, but the finger broke and it was a huge failure.
I then restarted the process of creating the mold and casting it using Quikrete. I created two molds instead of one to be more efficient as I needed two of the fingers. This time, I was able to create a much smoother batch of concrete, and I waited for about 2 hours and 40 minutes before taking it out of the mold. However, once again the cement still seemed very wet.
I tried carefully cutting the alginate to extract my fingers but one of them fell apart, and I was barely able to extract the other one. However, this one was very low quality and because the cement was still wet, all of the details of the finger became smudged.
The main problem with this assignment so far was that the cement was not drying. The alginate releases water as it dries, which prevents the concrete from fully drying inside the mold. The atmosphere that day was also not particularly dry. After more trial and error, I opted to use another brand of concrete, Rockite, to use as a casting material. With Rockite, I had to use much more cement mixture then what the instructions had entailed. However, the mixture dried pretty quickly and I was finally able to get two fully formed fingers. This time around, the cement dried so well that I was even able to pull it out of the mold without breaking it.
I post processed it using 400 grit sandpaper to smooth out the bottom edges.
I also spray painted it silver and used gloss clear coat afterwards.
Overall I am satisfied with how my fingers turned out, but it took too much time and effort for what it was worth. I ended up losing count of how many molds and casts I made in total (possibly 6-7). This assignment was probably the most frustrating assignment in my experience due to how messy is, and how you have to start over once you mess up. I learned that molding and casting is a tedious process, and could be very inconsistent depending on what you choose as your casting material.
Cost Analysis:
1 can spray paint: $4
https://www.homedepot.com/b/Paint-Spray-Paint/Rust-Oleum-Painters-Touch-2X/N-5yc1vZapz5Zbm2
1 can clear gloss: $4
Rockite Cement: $18.99
https://www.acehardware.com/departments/building-supplies/concrete-cement-and-masonry/ready-mix-concrete/18448?x429=true&utm_source=google&utm_medium=cpc&gclid=EAIaIQobChMIg5nZrK_05QIV0pFbCh0fEAWOEAQYAiABEgJG8vD_BwE&gclsrc=aw.ds
Alginate: $35.96
https://www.amazon.com/Alja-Safe-Lifecasting-Alginate-3-lb-Box/dp/B000KVSU60/ref=sr_1_4?crid=PFBIXDX1Z0H5&keywords=alginate+molding+powder&qid=1574101190&s=arts-crafts&sprefix=alginate+%2Carts-crafts%2C187&sr=1-4
Screws: $5.98
https://www.homedepot.com/p/Grip-Rite-6-x-2-in-Philips-Bugle-Head-Coarse-Thread-Sharp-Point-Drywall-Screws-1-lb-Pack-2CDWS1/100128601
Labor: 5 hr*$12/hr = $60
Total: $128.93
