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-   -   Paragon Kiln I use for Glass, can I put metal in? (http://www.lampworketc.com/forums/showthread.php?t=274890)

lunesse 2015-01-29 1:16pm

Paragon Kiln I use for Glass, can I put metal in?
 
A friend who is a knifemaker wants to heat treat steel etc., to use making knives.


My kiln is a digital Paragon GL18, big enough to hold his metals, and the temp gets high enough.

But will heat treating metal mess up the kiln somehow for glass, off gassing or oxidizing or something? I would love to help him, but not at the expense of my kiln being good for glass.

glassmaker 2015-02-05 8:17am

It's very unlikely to hurt anything. Many larger annealers - my own included - use metal racks to hold shelves. I've taken mine to the equivalent of heat treat temperatures before and never had a problem.

Edit: I just looked up the GL18 specs and see that it's only rated for 1700F. How hot is his heat treat? (Usually between 1500 and 1700F, I think.) Because of the low max rated temp, you may be taxing your elements a little bit if it's a long, hot heat treatment. If it was my own kiln I wouldn't be too concerned, but I might hesitate to recommend it to someone else.

Brad

snoopdog6502 2015-02-05 9:00am

It will not hurt a thing.

Speedslug 2015-02-05 10:24am

The onely thing that comes to my mind is mill scale and fumes.

I think you might want to make sure his work is cleaned well.

If you have a fiber floor a sheet metal pan might be called for.

But what is he working on that wood not be better served by torch heating is the question I have.

I get confused the details of metal hardening.
To get the metal hard it gets quenched in a liquid from temps high enough to make the metal red or higher.
To reduce the brittleness somewhat it is brought back up to something just under that red temperature, I think it 600 or 800 degrees and then allowed to cool with out quenching.

But this is all information from watching science shows on TV and when you add my faulty memory to the mix the reliability goes down alot.

Katia 2015-03-15 5:02am

Lunesse, you can in general. But some metals (for example, silver and silver clay things) will leave traces on the kiln shelf if you use the same shelf for your glass and metal things. Even if you use sheld primer or shelf paper afterwards. For example, if you put your silver pendant treated with the enamels on the shelf, fire it and then put the glass on this spot, you may end up with yellowish "shadow" of the previously enamelled thing (as it happens when silver foil, wire or clay is fused with glass - even a small amount makes the glass it touches yellowish, even clear).

To avoid this you may get a separate shelf for metals (not necessary expensive one. a piece of fiber board will do, just check out the temperature limits), mark it somehow and sligtly open the ventilation holes you most probably have (I am not sure about the model you have, mine is Paragon sc2 and the vent hole is on top - I just use a couple of kiln posts 1" high to lift the hole cover, to give the fumes an oportunity to go away. Do not put the metals directly on the bottom of the kiln - molecules of metals taken by the kiln may (not necessarily will, but) may react with glass for a period of time (numerous firings) spoiling the colours.

Steel is not that reactive but there is a matter of mechanical safety - by accident the hard steel (dropped from the tweezers, whatever) may destroy the inside insulation material.

theglasspilcrow 2015-04-04 6:28am

I had this same question regarding making beads on antique keys. I made and annealed a few like any 104, then read somewhere that annealing the keys in the kiln could mess up the elements. Does anybody have a reference for their thoughts that it is either harmless/harmful? I couldn't find anything other than word of mouth, and since I'm a kiln newbie I am very cautious.

Katia 2015-04-04 2:02pm

Annealing temperature is far below melting point of steel and iron (the same is for glass). So all you need is to ensure that your keys are not made from silumin (alloy containing aluminium, silica and other elements) or zamak (the name comes from Zink — Aluminium — MAgnesium — Kupher (copper)). These are widely used for decorative items and/or cabinet door knobs, for example (the weight of an item is considerably lower than of the same thing done from steel or brass and other solid metals).

If your keys are made from "real metal" and you organize placement in the kiln properly, - you should have no problem, the beads are normally annealed on steel rods and it is completely OK. If you do not use those low-cost and low temp imitations and pad your keys (or set on rod rests - whatever to prevent direct contact with the kiln inner surfaces and, of course, thermocouple and heating elements) to avoid any contamination from firing) - you will have no problem in the normal kiln "wear&tear" horizon.

theglasspilcrow 2015-04-04 4:34pm

Thank you for explaining Katia :-)

Speedslug 2015-04-04 5:34pm

I think the metals Katia is referring to are commonly called "pot metals".

Very light weight metal used in cheap knobs, handles and kids jewelry.

Katia 2015-04-05 12:08am

Phill, thank you, exactly, just couldn't find the right common word for this stuff. :)

lunesse 2015-04-06 3:44pm

Thanks so much, everyone! =)


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