Molding and Casting! | ENGI 210: Prototyping and Fabrication

For molding and casting, we used our hands to make replicas of our fingers with concrete.

First, I gathered all the materials needed, including measuring cups, alginate, rockite, water, two screws, a popsicle stick, a jig and a scale for measuring.

Using the scale, I then used a measuring cup to measure 6.75 oz of water and in a separate cup to measure 1.5 oz of alginate. This creates a 4.5:1 ratio.

I mixed them together by pouring the water into the alginate and then I mixed them with a popsicle stick until there were no clumps in the mixture. I then placed two of my fingers in the cup not touching each other or the walls of the cup.

I let my hand sit for at least 10 minutes until the mixture was set and then slowly wiggled my fingers out of their pockets without messing up the holes.

I then began mixing the rockite mixture to create the concrete fingers. I mixed in two different cups water and rockite with the ratio of 1:3.5 water to rockite. I mixed 35 g of rockite and 10g of water together and stirred with a popsicle stick.

Once the mixture had no more clumps, I poured it into the previous cup with my finger mold. I quickly inserted the screws which had been previously attached to the jig. I set the jig above the cup, so that it could hold the screws half inside the fingers while still having part of the screw exposed.

I then set the cup aside and came back an hour later to demold my fingers!

To demold them, I slowly pulled up on the jig, wiggling the concrete fingers around. They very easily came right out and then I scraped out the excess of the alginate and cleaned all of the cups as well as the scale I used.