Ramblin' Dan's Workshop

The Sanctum of Fine Art and Invention

1st Silver Cast at Home

I have already made a trial run with no wax to lose. Here I go for the real deal. Win or lose I'll show how the first attempt at casting silver in my own shop.

I can't show every step but I hope to get enough pictures that the general process is shown. In the future I make a list (no pictures) of every step and just post a link to it for those who want to know. Someday when I have a helper I may be able to post some action shots or a short video.

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The green wax is the part (the model) I want to make. The red wax is the spruing. A flask size is chosen to fit the size of the model. This is a 2.5x3 inch flask. The model is centered. You can see it is about 1/3 of way down in the 3 inch flask. It needs to be covered with at least 3/4 inch of investment.
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The investment has been mixed and is "boiling" under the vacuum in the chamber. This removes the air that might make bubbles or voids and actually helps mix the investment too. The investment is poured into the flask and it is being "boiled" under the vacuum again. The tape helps protect from boiling over in the chamber.
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The flask cover is removed after a two hour initial room temperature cure and here you can see the end of the wax sprue that will be melted out (and lost). Just popped into the kiln for wax melt out (300 deg) then slowly raised to 1350 degrees, held, then cooled to 800 deg casting temperature. This will take 10 more hours.

The Result

Unfortunately there is always room for error and I made a few. One at the start and one at the very end. A real crash and burn. However I am not afraid to call it a learning experience and forge er... cast ahead. Too bad about the pattern. That exact one is gone forever, but not the design.

I had a glitch when I did the silver pour. The crucible doesn't stay hot long enough for the cast, so I had to follow the melt to the flask with the torch still heating the silver puddle. When I poured I was a the wrong angle and I had a falter in the pour. It wasn't one quick uninterrupted stream. I immediately knew I blew it but I had to pour all the silver. 

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Almost enough to complete the design but almost doesn't count. I think the design was also too flat in the investment. Hard for the air to get out of the way. The vacuum only does so much. You can see the sprue is missing its legs. The sprue is also far too long. That was the early mistake. The sprue should be as short as practical or larger diameter. They can't be allowed to harden before all the silver gets in.
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Lesson's learned here is my next model all set to go when I get the time to run the kiln another 12 hours. I have one short sprue to help fill the small tab and make sure the melted wax can run out. I am ready to go again!

I am also starting some work on several new wax carvings. I want to be able to do several castings with each kiln heat. I can easily get three small flasks in the kiln and two of the larger ones. Even with failure I am eager to do more! Love it!

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