This week, our assignment was to mold and cast objects.
Because this was my first time molding and casting, I opted for the beginner assignment of molding my fingers.
I started out by mixing the suggested amounts of alginate (1.5 oz) and water (6.75 oz) into a silicone cup. After mixing for around 5-10 minutes, I stuck my pointer fingers in, and waited for around ten minutes. This was remarkably uncomfortable with the rim of the cup digging between my fingers. After the alginate set, I pulled my fingers out and began preparing the rockite.
I mixed 10g of water and 35g of rockite. This turned out to be more than enough to fill both finger molds. I slightly overfilled the two molds, set the 3d-printed jig for the screws, and left the rockite to set for 24 hours.
pulling out casted rockite
Thankfully, breaking away most of the overflowed rockite was relatively easy, and one of the fingers came out quite cleanly. The same couldn’t be said about the other finger, however, with the overflowed rockite being very solidly casted onto its base:
messy finger after removing as much extraneous rockite as I could by hand
I used a dremel to drum-sand off the extra material, and sandpaper to clean up the surface.
For post-processing, I decided to spray paint the two fingers. I stuck them into a small foam block and chose a metallic chrome color. I applied three coats and a glossy acrylic clear coat on top.
before paint
after paint
Overall, I think the fingers came out quite well; there were some small bumps and imperfections I neglected to sand off, but I think the casts captured an impressive amount of detail and I also like the shape of the bend. I’m also very thankful this wasn’t too heavy of a project.
Cost:
- alginate molding powder ($11.99 for 24 oz at 1.5 oz used): $ 0.75
- rockite cement ($18.99 for 10 lb at 35 g used): $0.15
- silicone measuring cups ($1.49 for 2): $ 1.49
- screws ($6.23 for 30 at 2 used): $0.42
- chrome spray paint ($6.48 for 11 oz. at 1 oz used): $ 0.59
- gloss acrylic clear coat ($8.99 for 11 oz. at 0.5 oz used): $0.41
- labor ($10/hr at 1.5 hrs): $15
total: $18.81, or around $9.41 per finger. Finally, a semi-reasonable price for one of these projects 🙂
Cleaned workspace:
