Path of least resistance...

[Cristi L]

Hello all...
I have a deadline and I have kiln issues.
For reasons much investigated, but still unknown,
My kiln will only get to around 1475.
I would love to finally figure this out, but right now
I have a deadline for some castings.
Which brings me to the question...
How long should I soak at 1475 for a casting?
One is aprox 15 lb, if that makes any difference.
Many, many thanks in advance-
Cristi

[Kevin Midgley]

That lack of your kiln's ability to rise to full temperature indicates a probable problem with one element.
Therefore how is your kiln going to be evenly heating or annealing?
Answer: it probably won't.
Fix the kiln is the answer you didn't want to hear but it is quicker and cheaper than doing the project over.

[Cristi L]

Darn it

[Morganica]

That's one of those "how long is a piece of rope" questions, anyway... A 15-pound casting might be a piece of glass about 10x48 inches and a half-inch thick, or a cube about 5 inches or so on a side. How long you'll need to soak it depends on the thickness of the glass, the type of glass you've got, and the way the mold is built.

You can tell fast enough if your kiln is heating and cooling evenly if you've got a pyrometer or a data logger and thermocouples around; just fire up the kiln and test. Or you can improvise with cones or stacks of clear glass squares, evenly distributed around the kiln. Soak at your top temp for 15-30 minutes, check the melt and stress patterns and see what comes back.

But I'd agree the answer probably won't be a happy one. And the problems usually get worse, not better.

[Cristi L]

again,
darn it
and
Thank you

[jim simmons]

Also, you can program the kiln to go afap to about 1200 or so, and then open the door and look at the elements.
If one set is dark, then you will know what the problem is and then continue to trouble shoot the problem'
Jim

That's one of those "how long is a piece of rope" questions, anyway... A 15-pound casting might be a piece of glass about 10x48 inches and a half-inch thick, or a cube about 5 inches or so on a side. How long you'll need to soak it depends on the thickness of the glass, the type of glass you've got, and the way the mold is built.

You can tell fast enough if your kiln is heating and cooling evenly if you've got a pyrometer or a data logger and thermocouples around; just fire up the kiln and test. Or you can improvise with cones or stacks of clear glass squares, evenly distributed around the kiln. Soak at your top temp for 15-30 minutes, check the melt and stress patterns and see what comes back.

But I'd agree the answer probably won't be a happy one. And the problems usually get worse, not better.