Ramblin' Dan's Workshop

The Sanctum of Fine Art and Invention

Prepping for First Home Casting

I have assembled a complete setup for doing my own lost wax castings in my own shop. My adult daughter and I took a class with the "Craft Guild of Dallas" on how to do wax carving and lost wax casting. I have published what I did in class elsewhere in this site and in the attached blog. 

Now I can practice all I want and do it all for myself without waiting for a class session. It is practice that makes perfect in my way of thinking. The class and instructor based training makes sure I am not practicing wrong.

I carved the Celtic Trinity Knot many months ago November 2013, as well as several other objects. Now is the time to prepare for casting.

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This is a special scale that can read to 0.10 grams. Here it reads 2.1 grams for the wax cross and the spruing. Weight in Silver = 2.1g wax and tree + 10% = 2. 3g X 10.36 = 23.828g silver. Call it 24 grams. Most of the weight is the tree. The black disk is the bottom of the flask and holds the tree as well as providing the "funnel" shape where the silver will be poured in the mold. The black rubber is removed after the investment hardens and before dewaxing and firing the mold.
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All the wax will be covered with the investment material and then melted and burned out of the mold. The wax is therefore "lost".  I jumped to a trial burnout shown here. I had to bend up this metal rack so air and heat could completely surround the flask. The kiln was fired at 1350 degrees after ramp up and held for two hours.
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I also had to make room bending the rack so this drip pan could fit under to collect wax dripping.  My trial run was with a flask I filled with investment but no wax model. So there was no wax to drip out. This galvanized metal will be fine to use as the wax melt out is at 300 degrees, then the pan is removed.
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I folded the corners so there is no way for the wax melt to run out of the pan. Wax would make a mess and contaminate the kiln when a lot of it is burned, That's a new flask on the left and the one I used in the trial run on the right. The metal rack is also scaled up pretty good in the heat.

HS238This is the sequence I followed when I mixed the Investment and programmed the kiln. My flask is 2.5 X 3 inches. I used 300 grams investment and 120 ML water. I have to be close but not critical. I used my vacuum chamber too!

I did this no wax model "hot run" so I would have the experience with my new equipment before I burned up the real wax model. With lost wax you only get one shot.

I learned a lot in this 10 plus hour investing and firing run. I am extremely happy I did the trial run first. I probably wouldn't have ruined the end result but I would have been a lot more nervous. Now I know I have a workable plan.

As I have said, this is a work in progress. So I will be adding to this article as I work on this project. The next sequence will be the real investment and the burnout followed shortly with the casting of the silver. I need another weekend to do this as I am not prepared to leave the kiln firing while I am off premises. 

My biggest lesson this time was how much heat the kiln sheds during this long run. And the best feeling was it all worked well.

I didn't have time to take a lot of pictures as I didn't need the distraction while doing the investment. It is time sensitive. There is not a lot to show during the kiln heat. I could have grabbed a shot of the flask before I disinvested it, but it looked like the other pictures here except for white ends...

More to come.

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