Types of glazes and firing cones

I have a lot to learn about glazing and kilns. I am signed up for Sunday coffee dip glazing and Beginner’s Glazing on Wednesday.

Are there types of glazes that we should avoid?

There are some lovely metallic glazes that I could use on some North Star Christmas ornaments but are they okay for our kilns? I’m specifically wondering about metallic glazes like AMACO Potters Choice Palladium PC-4, it’s such a beautiful color. There’s a gold one too. Do these require special firing?

The Crysatlex glazes are cool too but it says they fire at a cone 5. Is this too low for our kiln?

I don’t know about the others but we have the palladium. It’s lovely although it runs a lot. It’s fired in our regular glaze firing

Good to know! Thank you! I thought I’d make sure it was good before I purchased it.

Typically what you glaze at 5 is fine at cone 6 as well; in fact most of the sites where you can buy them will categorize them at cone 5/6. The colors may be slightly different between the 2 cones, but likely not much. Where it gets really interesting is I have some cone 04 glazes where the manufacturer states its okay up to cone 6, but the color difference is crazy.

Basically just stick with cone 5/6 and you should be okay. And as Amanda has stated some are known to be runny (palladium, oatmeal, and seaweed for ones we have). Jump on some glaze forums and you’ll get some good info quick. The Amaco Cone 5/6 exchange on facebook is a good resource.

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Almost all of the Amaco metallics are very runny but I’ve had awesome results with both Palladium and Saturation Gold. I highly recommend test tiles that stand up so you can measure the distance of run you get with the depth of application you are using. Also, a small tray with a lip to fire in makes everyone feel zippier about experimentation.

Spectrum makes a line of mirror glazes but, as a heads up, they are meant to fire to bisque temps. Doesn’t mean they might not be suitable, but whatever you are making would need to be sturdy enough after only 04.

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On that note the committee may want to reach a consensus about the cosmic tea dust lines that came out. We just finished test firing them at work and oof. Contaminated several pieces around it and as invasive as glitter. I think Satan himself formulated it

I’ve seen fired Granada at 05 and 5. It fluxed fine you just may not get as much wow factor at cone 6.

Danger-danger-danger!!! Never omit the leading zero in a Cone. Cone 05 is a different temp from Cone 5. 05 is low-fire. 5 is mid-fire/high fire.

That said, we could easily fire 05. The low-fire cone numbering is “upside-down”. Thus, the Cone 04 that we fire our bisque to is HOTTER than the recommended Cone 05 for the Crystalex glazes. If you’re interested in the Crystalex, you might pick one, and run a test tile in the regular bisque to see how it looks.

In general, if you have a glazed piece that you need to be fired in the bisque kiln, you’ll need to put a note on it. One of the “work” items on the board is “put pieces in the right place”. If you’ve got a low-fire glazed piece, some “helpful” person might put it on the Glaze fire shelf. If your clay isn’t low-fire, it won’t melt, but your glaze will not be what you wanted.

And – be aware that the Amaco metallic glazes don’t always come out metallic.