Lost Wax Jewelry Casting

Footage of my unsuccessful first attempt at casting

For my final project in my design for fabrication, we were allowed to “choose our own adventure” and create our own project. I decided I wanted to try lost wax jewelry casting. The process is as follows:

sculpt your jewelry out of wax
sprue the jewelry together onto a tree so metal can flow to each part
cast the wax mold in plaster
put the plaster and wax in an oven to melt out the wax
heat up the metal until melted
pour the metal into the mold
quench the mold and release the final metal part

For this project, I actually did 2 separate attempts because my first was unsuccessful. For the first one, I sculpted the jewelry out of machinists wax and for the second I used beeswax.

My second attempt at casting

Attempt 1

Sculpting

All of the jewelry for this attempt was made with machinist wax. I used this wax because it was available to me but did not realize that it’s melting temperature was too high for my purposes.

I used drills, files, and a soldering iron to make the machine wax rings. I then melted beeswax until it was malleable and sculpted it into the tree.

Plaster after peeling off the cup

Wax Melting

To melt the wax out I stuck the plaster in the oven when it was heating up and was at ~400C. I left it in there for 5 minutes and then pulled it out. At this point I assumed that all of the wax was melted out. There was a slight crack on the bottom of the mold.

Inside of the mold and crack on the bottom

Unmolding

I put the piece in water to release it from the mold. It was at this stage I realized that the machine wax had not melted out. The beeswax portion of the was all cast but none of the actual jewelry was cast.

Recovered jewelry and cast sprue

Machine wax rings and tree in paper cup

Plaster Casting

I glued the whole tree to the bottom of a paper cup and poured plaster around it.

A big issue I had with my plaster casting was that I had no vacuum to put the mold in. This means that it is much more likely that there are bubbles in my mold. I tried to counteract this by vigorously tapping and shaking my mold.

The next day when the plaster was dry I peeled the paper cup off of the

Mold fresh out of the oven

Pouring the Metal

I let the oven heat up to 900C and put the metal in there for 10 minutes. I used this website to calculate how much metal to use based on the weight of the wax.

I poured the metal into the mold and there was a lot of smoke and bubbling which was unexpected.

Cast beeswax and un-melted rings

Attempt 2

The only difference for this attempt is that I made all of the rings out of beeswax. It is a much softer material to work with.

I cast 2 rings this time and then made some pendants which are molds of my thumb and pinky fingers. I was curious to see the level of detail I could achieve.

Every other step of the process I kept the same. The results were much better using beeswax.

This went much better than the first attempt and most of the aspects were cast.

What I would do differently:

I would heat the mold so that the metal could flow through it easier
I would do more research on sprue-ing. I think some of my error is attributed to turbulence in my metal flow that could be improved by better sprue-ing.

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