Homework 8 Molding/Casting

PROCESS:

ROCKITE AND QUIKRETE

For this assignment, we were tasked with making wall hooks shaped like our fingers. Dr. Wettergreen asked us to use cement, rather than the plaster that we had used in class.

FINGER #1:

For the first finger, I began by making an alginate mold. The initial ratio I used was 3 parts alginate : 2 parts water by volume, and while stirring, I would add a bit more water until I deemed it the right consistency:

I then followed the instructions on the Quikrete bucket, and created a cement mixture that was ready to pour into mold. I poured the cement, and held my screw in place, awaiting the mixture to dry. However, this was not happening as quickly as I anticipated, so I secured the screw in place, and let the cement set until I came back (approx. 2 days later).

When I returned, the mixture was sufficiently dry, but would not pull cleanly out of the alginate mold. I got to excavating and got my finger to come out:

The final product proved to be kind of brittle. When I tried to sand some of the excess material left on the bottom of the finger, a little piece that I didn’t intend to fall off did. However, sanding did leave the material much smoother on the bottom that it had originally been:

FINGER #2:

For the second finger, I initially tried to use Quikrete as well. I went through the same processes as finger #1, but instead of waiting 2 days for the finger to dry, I waited about 2 hours (which is ~8 times longer than what is stated as necessary on the bucket). However, when I went to take out the finger, it was not bonded to itself whatsoever, and fell apart like wet sand.

Me and some other people reasoned out that the moisture coming out of the alginate while drying was causing the Quikrete some difficulty in drying in the appropriate amount of time. I decided to use the Rockite cement instead for my next cement, as I had seen that it had worked well for one of my peers.

The Rockite produced a much more expected effect, as it took about 25 minutes to dry completely:

 

This finger also looked a lot less rough around the edges than the one made out of Quikrete. I also sanded this one down appropriately. The only issue with this finger as opposed to finger #1 was that there was a small air bubble present near the fingertip.

POST-PROCESSING:

I also painted the nails on each finger and applied a sealant on them to prevent unnecessary wear and tear from handling.

I figured the fingers themselves looked a little scary, so I decided to keep the spooky theme when I went to paint the nails black with acrylic paint.

I accidentally applied some paint to the fingertip of finger #2, and wasn’t able to take it off. Whoops!

I then went out to apply the sealant, and left the fingers out to dry!

COST ESTIMATES:

Labor: $50

The whole process took about 5-6 hours, and I am valuing my labor at $10/hr.

Raw Materials: $22.20

Assuming I could have done the whole project with Quikrete, I would only have to spend $3.34 on a large bag of the material (https://www.masterwholesale.com/quikrete-concrete-mix.html).

1 lb. of alginate costs $6.95 on Amazon, and I used ~32 oz., so I would’ve bought 2 (https://tinyurl.com/s4zpg8j).

Acrylic paint is about $1 / bottle (https://painting-crafts.com/deco-art-americana-2oz.html?gclid=CjwKCAiA_MPuBRB5EiwAHTTvMcQKVmEAqIKVP5onIiBpBm74Fii9FGVtZs_TYDPVHF-86-Wa0Dly9hoC5GwQAvD_BwE)

The sealant I used was $3.96 (https://tinyurl.com/s22huep)

Machine Time: $0

I did not using any machines. All sanding was done by hand.

TOTAL: $72.20

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