Molding and Casting | ENGI 210: Prototyping and Fabrication

For this project, I was thankfully able to do most of the heavy lifting in class. My partner and I created the alginate mix, carefully measuring both the powder and water to create the perfect ratio. Then, since we had to do two identical fingers, I put both of my pointer fingers in the mix for five minutes and forty five seconds. We were told our mixture was a bit liquidy, hence the reason I kept my fingers in longer, just in case.

We then mixed the rockite with water and poured it into the alginate mold. We added the screws on top and I returned the day after to let the rockite set. When I returned, one of the screws did not set in the rockite because it was held up too high.

So, I removed the finger that had a set screw, mixed another rockite and water substance, and poured it into the same mold.

I placed the screw in at a height such that it would set, and returned the day after. Thankfully the day after it did set, and the two fingers looked identical.

After the rockite set and I had both fingers, I grabbed a small piece of foam, stuck the screws in the foam, and went outside to spray paint. Considering my favorite color is purple, I chose the purple paint. After shaking the can for a minute, I began to spray lightly in moving strokes about a foot away from the pieces. However, there was something odd going on with the nozzle. The paint wasn’t coming out right — it was barely trickling out, was inconsistent, and was coming out even after I took my finger off the nozzle. Below is a before and after.

Despite my efforts, this clearly was not going to work. I went back inside, grabbed a different purple, shook the can for a minute and began spraying the pieces again. This time it worked as intended. I did one full coat, waited about 3 minutes (as instructed on the can), and did another coat.

Then, I set an alarm for an hour and returned to spray the clear coat. I used the same technique as with the spray paint — shook the can for a minute, distanced around one foot, and sprayed light but moving strokes. After hitting all angles, I put it outside on the rack near the woodshop to dry for about thirty minutes (as indicated by the can).

I am intrigued to see if the fingers will actually be able to function as wall hooks and look forward to testing them out in the future when I’m not living in a dorm! Here is my final workspace, which was the grass where I spray painted and clear coated. It of course has some paint residue, but that’s inevitable and is the reason I spray painted in the grass — to avoid getting paint on the loading dock and other OEDK areas.

Cost Analysis:

10lb rockite = $0.37 for 70g of rockite
3lb box of alginate = $2.67 for 3 ounces of alginate
labor $7.50/hr = $15.00 for 2 hours of labor

Assuming the screws, water, popsicle stick, scale, beakers, spray paint, clear coat, mask, gloves, foam, and safety glasses are covered by the OEDK, the total cost is $18.04.