Objective: To mold and cast two fingers using alginate to create a mold and plaster to create the product.
Resources:
- Alginate (Mold)
- Plaster (Cast)
- Water (To mix with Alginate and Plaster)
- Screws (Attach to the end of the finger)
Tools Used:
- Cups (To hold alginate, plaster, water, and mixtures)
- Tape (To hold the screws in place)
- Styrofoam (To hold the fingers after casting)
Operation Costs: $45
- 2 cups of Alginate Powder and 1 cup of Plaster Powder ($20)
- 1 hour of work ($20)
- 2 Screws and one 2″-3″ block of Styrofoam ($5)
Operation Rewards:
- 2 casts of my right index finger
- Experience in using Alginate and Plaster to Mold and Cast
Process:
- Prepare Alginate Powder, Plaster Powder, and Water in separate cups
- Mix the Alginate Powder and Water in a cup with a 1:1 volume ratio
- Once the consistency of the mixture is “gooey”, insert right index finger in the cup for 8 minutes
- After 8 minutes, remove finger slowly so that the mold does not collapse
- Mix the Plaster Powder and Water in a cup with a 2:1 (Plaster to Water) volume ratio
- Once the consistency of the mixture is “gooey”, pour the plaster into the alginate mold
- Insert the head of a screw into the plaster, and hold the screw into place by using tape to hold the end of the screw.
- Repeat Steps 2-7 for the second finger
- Wait at least 30 mins for each plaster to set
- Remove the fingers from the molds, then attach the fingers to a Styrofoam block using the screws
Lessons Learned:
- Make sure to mix the water and alginate in a 1:1 ratio by VOLUME! When I tried to mix the materials using the ratio by weight, the alginate did not completely liquify, and it turned into solid clumps.
- When mixing the powders with the water, make sure to mix in every corner of the cup. Sometimes there are clumps of powder that like to “hide” in the bottom edges of the cup.
- If you want to have identical looking casts, make sure to use the same type of cup that holds the alginate molds. Since I had used different cups for each finger, I could not put the same amount of depth with my finger in the bigger cup compared to the smaller cup. This led to the finger cast from the bigger cup being shorter than the finger cast from the smaller cup.
- Don’t wear a nice jacket when you mold and cast! Powder flies everywhere, so there were many specks of powder found on my jacket after I finished the project.
- Give more time to post-process the casts! While I did not have enough time to post-process my fingers (I was out of town during most of the weekend), I would have used spray-paint to make my fingers blue (favorite color). I could also spray-paint the Styrofoam in a different color (silver, gold, grey) to accent my finger color.
Reconnaissance:
Alginate and Water Mix. The mixture is ready when it looks gooey (like slime).
Plaster Powder. While you do need a higher ratio of plaster powder to water compared to alginate to water, you only need enough plaster/water mix to pour into the finger mold, so you don’t need as much plaster powder as alginate powder.
Plaster Powder With Water Mixture. You must mix each Plaster and Alginate batch for each finger separately (instead of one big batch) because the plaster and Alginate both set very quickly (within 5-10 minutes).
Molding and Casting. This was the set-up of the screw-tape-alginate-plaster system that molded the plaster finger into its shape with an attached screw.
