Thursday, November 25, 2010

Glazes don't travel

The pottery truism reinforced itself this past week - glazes don't travel. I think this usually refers to the fact that different suppliers will have slightly different chemicals. RIO from one supplier may be less or more pure than RIO from another supplier. But what I have found is every kiln in the entire world is different. And glazes react differently in every kiln. Glazes that work perfectly in one kiln may not work in a similar kiln.

I got my first batch of pottery glaze fired at the new studio. It was ugly. I had used all glazes I had previously used, tuned, tweaked for cone 6 oxidation firing in an electric kiln. The new studio uses cone 6 oxidation firing in an electric kiln so I figured I was money. Not so much.

My lorio ash? Seriously over fired. All webbing and definition was gone. Just an ugly tan mess. A lot of crystals.

My seiji nuka? Same - over fired. Ran and pooled into dark brown nastiness. No lovely green.

The Bailey's red that is one of my favorites? Came out almost black. No idea what happened with this glaze. The others were obviously too fluxed for the kiln and require some tweaks to bring them into line with the new kilns. This totally different color perplexes me.

The only glaze that worked was a floating blue. Probably my least favorite glaze. I only use when someone asks specifically for it (in this case my wife asked for a large bowl with "that blue"). It melted correctly, looks perfect.

So my next project is extruding several dozen test tiles and going to work refining my standard recipes to work in these new kins. They fire a hotter cone 6 and appear to take longer to cool off than the kilns I have worked with in the past. Seems like I should be able to make use of those traits... I will dust off some crystalline glaze recipes.

The very good news out of this batch was all my tumblers I was going to put decals on came out. I will be doing my first batch of decals over the weekend. Should get them fired in the next couple of weeks.

No comments: