my fingers… | ENGI 210: Prototyping and Fabrication

This week we learned how to mold and cast something by making replicas of our fingers.

First, we needed to make the negative (as we already had the positive attached to our bodies). We attempted to mix the correct ratio of alginate and water with a balance, but it kept auto-taring and so the numbers were running away. We moved ahead, instead eyeballing the ratio by volume, and mixed up the alginate with popsicle sticks. Once our mixtures weren’t clumpy, it was time to cast.

Whatever positive you are casting must go into the goop. Fortunately for us, this was our fingers. From what I remember the alginate took 10-15 minutes to set, so it was a brief yet awkward period of time.

After our fingers were freed, we mixed plaster of Paris to pour into the alginate (which is now a negative mold). Once filled, we needed to place screws head-down into the plaster so the fingers could be affixed to something once set. The teaching team printed many plastic jigs for us to use, but the placement of my fingers in the alginate did not align with the mounting holes. I didn’t want crooked mounting screws, so I looked around to see what I could use and set my eyes on the extra popsicle sticks laying on the table. Working quickly (since the plaster of Paris was now in the process of setting), I jury-rigged something to hold the screws in the correct spots. Sorry, no pictures of this since it was done in class.

We left these to set for a few hours, then came back to de-mold. When removing excess plaster I accidentally cracked the base of one of the fingers, but managed to fix it with super glue. I also smoothed over edges with sandpaper and used pliers to remove any plaster from the screw teeth.