Who doesn’t want a human finger sticking out of their wall? I am a little disapointed that I am going to have to wait for next Haloween to get the full effect! This project was a fun and straight forward one. I think I lucked out since I had already used the plaster of paris which was objectively easier than the concrete but I still learned a lot. So here we go!

The first challenge of molding and casting is mixing your medium. We used alginate as the medium we placed our negative into. alginate is cheap, fast drying and simple so that makes it an ideal media for this sort of work. I mixed it according to the ratios online, curled my finger in there and waited for it to dry. This took about 15 minutes and I kind of enjoyed the excuse to just do nothing. When I felt it was safe to remove my finger I gently pulled it out and waited for the algenate to get a little more firm while I fetched the plaster.

The plaster I mixed a little differently. To mix the plaster I started with about a third of a cup of water and sprinkled plaster dust into the water untill the two were at a nice ratio. Next I stirred gently with a stick untill I was sure no pockets of powder were holding out on me. The biggest risk I found here was that if I stir too vigorously then I introduce air bubbles to the plaster. Plaster is still a fairly inviscid fluid so the bubbles seemed to be able to escape for the most part if I gave them a little  If I had been working with something a little more viscous then I likely would have had a problem at this point. When the plaster was well mixed, it was time to pour it into the alginate mold. I poured it in carefully and when the plaster seemed to have filled the finger hole I picked out the mold and rotated it around a few times. This allws the plaster to finto the upward angling part of my finger tip. Sure enough a massive bubble escaped when I did that so looks like I dodged a bullet. Once that was done I added some extra plaster for good measure and suspended a screw in the back for wall mounting. One of my screws ended up at a bit of a weird angle. I think this is because we ran out of large popsicle sticks and I tried to suspend tape across the top over the plaster. This worked well enough but this wall hook will not be going in my wall at that angle I think.

I gave the plaster overnight to solidify a bit and came back the next day to break the mold. Unfortunately the alginate is just too soft to save so I had to tear it a bit to extract my finger. When the alginate was off I gave my finger another couple days to dry out. Alginate is a very moist media and the plaster just can not fully dry out when it is still inside. Finally I sprayed it with clear coat and enamel to make it last!

Overall I learned the basics of molding and castng in this project. I had the oppertunity to make something cool and learned some of the details about proper plaster mixing, when to demold and how to suspend a screw so it stays straiight. The fingers came out with minimal air bubbles and enough detail to even see my finger print but the screws came out a bit angled and the end of my finger is a little choppy. I am looking forward to perfecting molding and casting!

Material Cost

Plaster of Paris:  $0.25 (a very small amount of a $5 bucket)

Alginate: $0.30 (a cup or so of a 7 dollar bag)

Clear Coat/Enamal: $0.05

My Time: ~1 hour $10

 

Total: $10.60 for 2 pieces