Over the past few weeks, I have been working on the ENGI 210 “Molding and Casting” homework, in which we were given alginate and plaster, and told to cast and mold replicas of our own fingers in order to make wall hooks. This blog post will cover my process, areas for improvement, and cost analysis for my finger wall hooks.
(Note: Forgive me for using different paint on my two fingers – I have explained why I did this later in the blog)
Figure 1: My final two fingers.
My Process
Our entire class began this assignment together during class one evening, where we learned how to mix the alginate with water to create the mixture that we would make our molds out of, and how to mix the plaster with water to create the material that we would use to cast our fingers using the mold. We were told to mix the alginate with water in a 1 parts alginate to 4 parts water by weight for the molding mixture, and to mix 1 part plaster to 1 part water by volume for the casting mixture.
Figure 2: The alginate I used to create my molding mixtures.
Figure 3: The plaster I used to create my casting mixtures.
My first cast was a bust – I apparently mixed way too much water with my plaster, because when I came back the next day to check on my work, everyone else’s had totally solidified and mine had solidified only inside my fingertip – the rest of my finger was essentially dirty water. I gave up on this cast, threw away the mold, and began from scratch.
Figure 4: Side-view of the mold.
I followed the same process the second time around, except I put two of my fingers into the mold in case one of them ended up breaking on the way out. Both fingers ended up coming out of the mold just fine, but did not have much detail – you couldn’t really even see the outline of my fingernail. Nonetheless, I moved forward with them, spray-painting them brown and following up with clear coat. In the end, with the limited amount of detail the cast picked up from my finger, coupled with the brown spray paint, my fingers ended up looking like turds, which I really disliked. Two days before this assignment was due, I decided to do another two-finger cast in order to get a better product to turn in.
Figure 5: Top-view of the mold after the fingers were removed.
Figure 6: My brown fingers after post-processing.
Figure 7: The brown spray-paint I used.
Figure 8: The clear coat I used.
My third time around, everything went smoothly, except one of my fingers broke in half while I pulled it out of the mold. The second finger from this mold, however, turned out fine and actually had great detail, even clearly showing my fingerprint. Since I disliked the look of the brown spray-paint I used on the previous fingers, I decided I could deviate from my original design ever so slightly as to apply a green spray-paint instead of brown with a similar coating of clear coat afterwards. They are from the same company, the same type of paint – the only difference is in their color.
Figure 9: The front of my third finger.
Figure 10: The back of my third finger.
Figure 11: The green spray-paint that I used.
In the end, I took the better of the brown fingers and the new green finger to be my final two fingers to turn in.
Areas for Improvement
I think most of my room for improvement comes from my first set of successful fingers (the brown ones). They were of poor quality from the start – perhaps I had made the alginate mixture too thick, because it simply had not captured the details of my fingers very well, yielding a finger that looked much more like a turd than a finger, a comparison which was made even more dramatic by my poor choice to use brown spray-paint in my post-processing. If you want to judge for yourself, have a look at Figures 1 or 6.
I chose the better of the two brown fingers as the one to turn in alongside my green finger, but even the “better” one was lacking many fine details of my fingers that can be seen in my green finger. I probably would have benefitted from doing a fourth mold and cast, but there was very little time left and also very little alginate, and I figured some of my classmates might have needed it more than I did.
Cost Analysis
For this project, the elements that could have accrued cost are the alginate, plaster, the cups we used to mix alginate and plaster in, the various paints, the screws, and the opportunity cost of my time. I will assume that the wood sticks I used to mix the mixtures and the water I used in my mixtures to be of negligible price since they are cheap and easy to come by.
Alginate
Our class was provided with a 5lb bag of “FaceGel 590” alginate, which costs $52.15 online. I used roughly 2 cups of the alginate – nowhere near the whole bag, or even a significant portion of it. I will make a generous estimate of $2 for the amount of alignate I used.
Plaster
Our class was provided with a 25lb bag of Plaster of Paris, which I have found to cost around $20 from various online retailers. For my project, I used significantly less plaster than alginate – I believe I used well under 1 cup of plaster. I will make a generous estimate of $1 for the amount of plaster I used.
Cups
Although the cup I used is technically reusable, I personally would not want to mix anything else in it, given how dirty it got. For this reason, I will consider the full cost of the cup in my cost analysis. I found a silicon cup similar to the ones we used in class online for sale for $6.32. Therefore, I will estimate $6 for the cost of the cup.
Various Paints
Most retailers seem to sell cans of the spray paints and clear coat I used for around $5. I did not use anywhere near the entire can for any of the paints, but it is impossible to know how much of the cans I used since I cannot visually see how much of the contents are left. Therefore, I will make a generous estimate of $2 for the amount of paint that I used.
Screws
In my two fingers, I used 3 screws. Roughly 150 of these same screws can be purchased online for $5, so I will estimate that I used about $0.10 worth of screws.
Opportunity Cost of my Time
Most of the time this project took was spent letting the plaster dry overnight while I was elsewhere. I spent about 4 hours of my own time actively working on this project, and my time as a Tech TA is valued at $12/hr. Therefore, the opportunity cost of the entire project is $12 x 4 = $48.
All together, the total cost of this project is $2 + $1 + $6 + $2 + $0.10 +48 = $59.10. As usual, a large portion of the cost of this project is associated with the time it took me to create it. Really, for a 2-finger mold and cast, it would only take around 30 minutes to do the mold and cast, and maybe another 30 minutes for post-processing, so now that I am more familiar with the process, I could probably reduce this cost quite significantly. Even so, this is a relatively low-cost project compared to the other assignments I have done for this class. I believe it might be the cheapest so far, in fact.
