Ramblin' Dan's Workshop

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A Grate Experience

The word grate is spelled correctly. I am referring to the grate in my Paragon E-12T Kiln.

The first part of silver lost wax casting is burning the wax out of the mold. This is done by elevating the flask(s) above the bottom of the kiln and using a collection pan to catch the wax as it flows out of the investment. This is done at 300 degrees for a few hours then the wax pan is removed. The kiln then heats up to 1350 degrees or higher for a few hours to actually burn out the wax and cure the investment into a hard shell.

The grate is remains in the kiln and must withstand this high (bright red) heat.

I first used a plain expanded carbon steel grate. It was inexpensive and I could bend it to a channel shape. It could support itself and I could get the wax pan underneath. This has worked well for about a year, but the extreme heat was taking a toll on the grate. It was oxidizing heavily and a lot of scale was coming off after each heat. The steel was actually getting thinner. The heat was really softening (annealing) the steel.

In my last firing the grate sagged in the middle and the flasks were almost tipped over. This is not a good thing and that was the last time I could use that steel grate. Time to find or make a new one.

I didn't like the scale that was coming off the grate on each firing so I went a new route. I purchased a 12" x 12" square of 9 gage x 3/4" expanded metal. This time it is stainless steel. It is so tough, I could not bend it like the old grate. So I cut a plate to fit the kiln and then elevate it with ceramic kiln furniture. The furniture is the square looking posts that are 1" high.

There are 1/2" high furniture posts under the bottom plate that have always been there. 

I have not yet done a kiln heat with the new grate, but I expect no problems. I assume it won't scale any worse that the stainless steel that is used to make the flasks. The flasks darken from their shiny new condition but do not scale off any rust. So it should be a great grate experience.

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 The top grate is the old one. Very soft and scaled. That's the leftover piece of stainless. Extremely hard to cut...  The old grate is what is called "flattened" expanded metal with welded connections. The new stainless material (bottom) is purely expanded and much heavier.
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 I had to cut the SS grate to fit the bottom of my kiln. I DO NOT want to get the metal too close to the heating elements!  This is the 1" high furnature posts I ordered. I had to order two 4 piece sets, so now I will have two as spares.
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 Just enough room to get the wax pan in place. It doesn't stay in for the high heat so it is just galvanized steel.  This is the configuration for the high heat with the wax pan removed

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