For this week’s assignment, the goal was to learn the processes of molding and casting through using the shape of our fingers to create coat hooks and it was completed using the following materials: alginate, water, cups, popsicle sticks, plaster, concrete, tape, and screws.
The first step in the assignment was to create the mold. I made the mold by mixing a 1:1 ratio of alginate and water in a cup with the popsicle stick. After mixing for about 4 minutes, the mold was ready and I inserted my crossed fingers into the alginate. After another 3-4 minutes, the alginate hardened and I pulled my fingers out slowly to make sure the mold wasn’t altered. This step took a few trials to get down as for the first few, I would stop mixing too early and I my finger would have to be in the mold for extended periods of time before the alginate hardened.
For the next step of casting, two different materials were used. For the first set of finger hooks, plaster of paris was used for casting. In another cup, I mixed the plaster and water in a 2:1 ratio and poured it into the cavity of the mold. As air bubbles are common when pouring and can cause the final product to break easily, tapping and shaking the cup to get rid of air bubbles was necessary. A screw was then placed head down into the plaster and taped onto the walls of the cup to set along with the plaster product. The alginate set after a few hours but when I tried to demold the finger by pushing it out, the finger ending up breaking. I repeated the process again and used a knife to cut the mold out but due to unforeseen air bubbles, the finger broke apart again. I wanted to use the plaster for more trials but the OEDK was fresh out. As such, I resorted to using concrete. It was essentially the same process in terms of casting but the concrete takes much longer to set so I couldn’t have many run throughs using it. A picture of the mold with the screw and concrete in it can be seen below:
Final Mold With Screw and Concrete
After removing the mold of the fingers, this was the aftermath:
Mold After Being Removed From Fingers
The finished product can be seen below:
Two Sets of Crossed Fingers
The discoloration in the finished work is due to cracks that appeared after demolding. I wanted the piece to be rid of such imperfections but didn’t have the time to make more pieces so I created more concrete solution to put inside the cracks. A closer view can be seen below:
Close Up Of Crack Filling
Other Side of Crossed Fingers
Cost analysis
The total materials used are as follow:
- 400g Alginate (100g per cup; $35/3 lbs)
- 100g Plaster (50g per cup used; $17/25lbs)
- 100g Concrete (50g per cup used; $8.97/10lbs)
- Cups, Screws, Popsicle stick, tape – negligible due to amount used
Total Material Cost = (400g * (1lb/454g) * $35/3 lbs) + (100g* (1lb/454g) * $17/25 lbs) + (100g * (1lb/454g) * $8.97/10 lbs) = $10.62
Time used:
- 30 minutes to create mold and cast solution for each cup – 2 hours total
- 30 minutes troubleshooting each concrete piece after demolding – 1 hour total
Total Time Cost = 3 hours
Approximating 1 hour of time to $5 gives a total cost of $15.
Total Cost = $15 + $10.62 = $25.62
