Saturday, April 28, 2012

'Minford Silt' glaze?

We're preparing to fire the wood-fired kiln tomorrow, and I've decided to glaze quite a few pots this time using this wonderful material an unknown customer brought me from Ohio a few years back. He called it a blue clay.

It's great stuff. I actually threw a pot with it and bisque-fired it to about 1800 degrees F. It had a nice ring to it. But when I fired a small piece to 2,200, it melted. So, I started using it as a glaze. Fired to cone 10 and above, it produces a nice brown glaze and reacts well with natural ash.

I can brush it on a wet pot right after throwing, and I can dip a bisque-fired pot into it, no problems. I wish I could find some more. I've only got half a 5 gallon bucket left.

I searched online and found an old post on Clayart by Steve Blankenbeker a ceramics engineer working at Cedar Heights Clay Company who was posting about research into finding a clay like Albany Slip which used to be a popular glaze among old-time potters until they stopped mining it. He states that there is a glacial deposit of clay in southeastern Ohio called "Minford Silt" that is similar to Albany Slip, but requires a lot of flux to get it to melt.

My customer must have found the deposit he was hoping to find. I wish I could locate that customer.

Apparently, this material I'm using is an alluvial clay, a sediment that has been deposited by water from rivers or streams.

I just know it feels good on my hand when I mix it. It's so soft and slippery. And it seems to love the atmosphere inside my wood kiln.

Ohio Clay slip

Here's it's sprayed on a bisque-fired tree platter

Ohio clay reduction cooled

Ohio clay - heavy reduction

Ohio clay cooled quickly
 
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