For our final homework assignment we were tasked with casting two fingers as hooks (and post processing them) to experiment with shape transfer. I found this homework to be fairly straightforward and quick, at least in comparison to our previous assignments. 

The first step in the process was to create a negative mold of my finger. As we did during class, the material for the model was made by mixing alginate with water. Specifically, I used the 1:4 ratio (by weight) and mixed 2 oz of alginate with 8 oz of water. In my first attempt, the mixture did not turn out as I had anticipated. Even though I had mixed nonstop, the result was lumpy and sticky.

I tried again with the same proportions of alginate and water and was successful! I chose to mold my index finger so as to minimize the amount of concrete I would need to fill it in. Since the alginate was already fairly dense when I inserted my finger, I only had to keep it in place for a few minutes before the alginate had solidified.

My next step was to make the casting material. To do so, I approximate the amount of Rockite I would need and mixed the cement with a few ounces of water. I immediately realized that I had poured too much water because the mixture was watery while I had to have the consistency of thick batter. I started over and mixed the cement and water together, this time with barely any water. I slowly pour more water as I saw fit. Once I reached a consistency I was happy with, I slowly poured the cement into the mold. To try and prevent air bubbles, I rolled the mold around to ensure the cement had reached all the points of the mold.

The final step before removing the finger was to insert a screw into the cement. I picked an 8 x 1 ¼ in wood screw and placed it in the finger when the cement was still liquid, but dense enough to hold the screw in place. After waiting for approximately 15 minutes, the cement was dry enough to be removed from the mold. I removed the finger very carefully because I wanted to prevent breaking the finger and the mold.

To my surprise, I was actually able to both remove the finger cleanly while keeping the mold intact. This facilitated my molding process a great deal because I didn’t have to make a new mold for the second finger. I mixed more concrete and repeated my previous steps to make the second finger. Since I used the same mold for both fingers, they both turned out to be almost identical.

However, one difference between them was that they had some tiny holes on the bottom. I spoke to Adulfo about the cause of these holes and he attributed them to holes in my alginate mold. He suggested that next time I use the vacuum to remove potential holes in the mold before casting.

Now that I had both fingers dry and ready, I began post processing. The fingers had some excess concrete at their base, which I used the belt sander to remove. I then used sandpaper to smoothen smaller artifacts in each finger. Finally, I decided that I wanted to give my fingers a metallic look. To do so, I spray painted them first in gold and second with a clear gloss. Because I wanted to evenly paint the fingers all at once, I tied them to a string and held them up with one hand as I used the other hand to spray the paint. My technique somewhat backfired because I got a bit distracted holding the fingers up and sprayed the paint too close to the fingers. I ended up sanding the bits of the fingers that had too much paint and reapplying the paint and gloss.

In the end, the fingers didn’t come out as identical as I think they could have, but I’m happy with the outcome nonetheless.

 

Cost analysis

Labor

• Approximately 3 hours of labor, $15/hour = $45

Materials

• Alginate 3 lb  bag sold for $23.36 from Reynolds Advanced Materials. I used ¼ lbs, so 3/0.25= 12, $23.36/12= $1.95
• Rockite tub (10 lb) sold for $18.99 at Ace Hardware. I used ¼ lbs, so 10/0.25= 40, $18.99/40= $0.47
• Gold spray paint sold for $3.99 at Target. I used approximately ⅕, so $3.99/0.2= $0.80
• Rust-Oleum Specialty Clear Triple Thick Spray sold for  $13.17 on Amazon.  I used approximately ⅕, so $13/17/0.2= $2.63
• Mixing cups (pack of 100) sold for $36.96 on Amazon. I used 3, so $36.96/100= $0.3696, $0.3696*3= $1.11
• 8 x 1-¼ screws  (100 pack) sold for $6.25 at Home Depot. I used 2, so  $6.25/100= $0.0625, $0.0625*2= $0.13

Total: $45 + $1.95 + $0.47 + $0.80 + $2.63 + $1.11 + $0.13= $52.09