For our last homework assignment, our goal was to mold and cast two of our fingers. The process for completing this was deceptively simple. In class we learned how to mold and cast with using plaster and it went relatively smoothly.

First I mixed 9 oz of water with 6 oz of Alginate. I would add some some more alginate or water depending on how thick the mixture was while churning.

Then I stuck my finger in the alginate and held it there for a couple minutes until the mixture solicited and I felt that I could remove my finger without destroying the mold.

We then mixed the plaster and poured it into the mold. While pouring in the plaster I made sure the move around the mold and tap it on the table to ensure that all air bubbles were removed and that the plaster reached all portions of the mold. After drying, the finger came out pretty well and I was happy with it.

All I needed to do was cast one more finger to complete the assignment. However this simple task and a lot more troubles than aI anticipated.

Wrong Cement

The assignment specifications were recently changed and we were ti make our other finger out of cement instead of plaster. I thought this would be a little more annoying but I had no idea how much so. I poured two molds full of the Quikrete and let them sit for a couple hours.

Unfortunately this cement was mean tot are multiple days to set and with the alginate leaking water into the mold as it was supposed to dry, the finger broke upon my extraction attempts. I tried to use this device to extract some of the water but it did not help much.

 

Since this cement needed much more time to dry, I knew I had to change my caster material to something with a falser drying time. I then tried out the Rockite cement and it dried in about 15 minutes!

The finger came out of the mold nicely and I thought I would be done at this point.

The Air Bubble Situation

Unfortunately the finger that I removed from the rockite had an air bubble on my fingertip from improper pouring technique. I thought that I was pouring it well and had been banging it on the table to remove the air bubbles but I might have had to do more for the cement than the plaster.  I then made my 5th alginate mix and mixed another round of the Rockite to pour into the mold. On this mold I curved my finger less so there would be a lower probability of an unreachable air bubble

This time I made sure to pour carefully, rotate the mold as I was pouring so the cement would reach all portions of the mold, then bang it on top of the table to remove any final air bubbles. In the mean time I spray painted my previous fingers gold and clear coated them afterwards. I figured that I could turn in the finger with an air bubble if I had to but it would be preferable to have no defects. Later when I removed the finger, there was another air bubble on my finger tip.  This was pretty frustrating and I wanted just turn in the fingers that I had already completed since my attempt at fixing the defect failed.  But I deciding to make one last mold so I could make my homework the best it could be.  I made another alginate mold and made sure to curve my finger one less. I then prepared and poured the very limited supply of Rockite carefully into my mold.

30 minutes later, I check on my mold and decide it is ready to remove. As I am removing it, the mold looks good until I reach the finger tip which had ANOTHER air bubble.  At this point I was really frustrated and we had essentially run out of Rockite.

Once I finally chilled out, I made a 7th Alginate mold and mixed the last bit of Rockite. Since the supply of material cause this to be my last mold, I made my finger mostly straightened so there would not be any room for air bubbles.  I made this final mold and after 30 minutes, I removed a fully intact finger. While it did not look like my initial plaster finger, it had no defects so I was very relieved.  I then spray painted and clear coated the finger which finally brought a conclusion to this assignment.

Cost Analysis:

Labor:

$15/hour x 7 hours = $105

Material Cost:

10 lbs of Rockite Cement: $18.99

Alginate: $13.20

10 TCP Global Mixing cups: $10.96

Total: $148.15

Overall this assignment took a lot more time and money that it should have. With a skilled caster this could have been completed I under an hour which would have covered the labor cost by $90.  Also I did not need the full 10lb bags of Rockite and alginate to complete these mold but those were the cheapest available buying price.

 

Sources:

https://www.acehardware.com/departments/building-supplies/concrete-cement-and-masonry/ready-mix-concrete/18448?x429=true&utm_source=google&utm_medium=cpc&gclid=EAIaIQobChMIurWV4K305QIVY_7jBx1oCwVPEAQYASABEgIksvD_BwE&gclsrc=aw.ds

https://www.dentalplanet.com/shop/product/c302070-zhermack-hydrogum-5-alginate-canister-refill-lilac-453g-1-lb-bag-198481

Pack of 12 – Mix Cups – Pint size – 16 ounce Volume Paint and Epoxy Mixing Cups – Mix Cups Are Calibrated with Multiple Mixing Ratios