Background:

The molding and casting is a brand-new experience for me. The goal is to create two casts of my index finger using plaster and alginate.

Part 1:  Preparing the alginate and plaster

Initially, I measured 57g of alginate powder to be used. According to the instructions, the alginate to water ratio was 1:1. But when it comes to the real-life operations, the volume was hard to determine when one ingredient is powder and the other is liquid. As a result, I used approximately a alginate to water mass ratio of 1:4 to prepare the mixture.

I added the water to alginate slowly to ensure it is not too liquidy. At the first stage, the mixture was a dough-like texture. With more water added into it, the mixture became more like a state between solid and liquid. When the mixture had no more chunks of material inside and the surface of it became nearly smooth and glossy, I stopped stiring it and started to place my index finger in the mixture.

After 5 minutes, the alginate became a gel-like solid and the mold was created.

Part 2: Preparing the plaster solution

Initially, I measured 20g of plaster power. According to the instructions, the plaster-water ratio should be around 2:1. I assumed this ratio to be the volume ratio and roughly estimated the portion of water and plaster. After mixing them together, I found out that I can still somehow see through the mixture. As a result, I added about 8g more of the power inside the mixture and stirred it until it became a creamy white liquid. Finally, I poured the plater solution in side the mold I made before.

Part 3: Adding the nail

I drill a piece of tape through using the tip of the nail and stick the piece of tape where the nail can be left in the middle of the plaster.

Part 4: Post-processing

This is the look of a single finger coming out of the mold.

The exact same processes described before were applied to the second finger. The post processing work mostly include spray painting a clear coat enamel onto the fingers to protect the surface.

The final products is shown below:

 

Successes and Limitations:

Successes:

The delicate details of the fingers are all produced without major artifacts or deviations.

There were no gaps or grooves that would damage the appearance of the casts.

The fingers were coated with enamel to protect the surfaces.

Limitations:

One of the limitations would be that the fingers were not bent enough to be like a real hook.

Another limitation would be that a small base could be added to the finger hooks to add more stability. This could be accomplished by adding more plaster solution when casting the fingers.

Cost estimations:

Material:

Alginate: $0.02/g * 114 g = $2.2

The cost of plaster was about $0.002/g * 40g = $0.08

Labor costs:

2 hr * $15/hr = $30

Total costs: $2.2 + $0.08 +$30 = $32.28