Going into the casting/molding project, I was really excited to work with some materials I had never used before, including alginate and plaster.  I had done some work with silicone molding in the past,  but never with molding something as intricate and detailed as my own finger!

Making the Mold/Pouring the Plaster
In class, we mixed water with alginate powder and I stuck my finger into a cup full of alginate for about 10 minutes until it was hard enough for me to slip my finger out of it without breaking the mold.  After that, we mixed water and plaster in order to pour it into the mold.  Lastly, we dropped a screw into the plaster so that the finger would have something we could use to stick it into a wall.  The fingers were designed as wall hooks, so I bent my finger slightly when I put it in the alginate so it would be able to hold something up like a hat.  I let the plaster cure overnight and came in the next day to find a perfect recreation of my finger encased in plaster!

Results

After making the first finger, I repeated the same process and used the same mold to make another copy of my finger.  However, this one likely had a slightly unbalanced mix ratio of water and plaster, so it came out very weak and I broke the screw off the finger when trying to demold it.  In order to safely get it out, I had to rip the alginate mold apart and the finger that came out felt extremely delicate.  Here is a photo of the second finger after being removed from the alginate mold and the two fingers side-by-side.

What I Learned

Beyond learning how to work with alginate and plaster, I learned that I need to be more careful with the mix ratios when mixing things like plaster.  I eyeballed it both times because using the scale would have required waiting a lot longer to pour the plaster; I got the right ratio the first time but clearly not the second time.  Next time, I will be sure to properly measure everything out by weight and will likely end up with better results.  I also learned that alginate and plaster are really cheap and easy materials to work with; I am going to incorporate casting and molding into many of my future projects because of how simple it is to get amazing results.

Cost Analysis

Labor: 1 hour at $15 an hour = $15

Plaster: $10 for a 4lb bag = <$1 (I used very little)

Alginate: $40 for a 3lb bag = ~$4 (we used a few ounces in total)

Screws: Very cheap (we used two total, found at OEDK) and can be ignored = $0

Mixing cups were a shared resource = $0

Overall, it cost around $20 to do this project, including labor and materials cost.