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Member Since 24 Nov 2012
Offline Last Active Jan 17 2013 10:52 PM

Topics I've Started

Pit firing

16 December 2012 - 12:42 AM

One of my traits is that I don't mind asking odd questions that betray my ignorance. But –

Briefly, as in the last twenty minutes, I've been looking at pit fired pots. I know that the pit fired pot isn't useable or water tight because it isn't covered with a glaze. BUT – could you:

Pit fire,
and then High fire with a glaze?

Could you keep the same fun colors that you get with the pit fire in a high fire, or would those things burn off?

Glaze and clay exploration

04 December 2012 - 01:43 AM

I hope this is ok: I'd like to make a thread about my own searches in glaze and clay formulating. The idea is that this would be a helpful resource, based on what I've read and the help I've recieved from my art teachers (ceramics or not – for example, my printmaking teacher is quite wise in areas that touch on clay.) I encourage anyone to comment about the stuff I post here. I'll most likely edit this top post as time goes on to add glazes, clay mixes, edit for content, edit for format, and add photos of the glazes.

Porcelain, cone 10.

Tile#4* 24
EPK 16
OM4 Ball Clay 20
Silica (Flint) 18
Custer 22

*When I first mixed this, it was Diamond. For the main thing, my teacher suggested I get Tile#4.
I've decided that I absolutely love porcelain, and that throwing with it is wonderful. I've read a bit on formulating a porcelain clay here. Based upon a formulia I found online, and my teacher's insight, here is the clay that I'll be making next semester. I'm going to age it too; I'll be buying it as I'm able and will add some vinegar and other aging agents. If you guys have any thoughts on how this mix will be this next semester, I'm eagerly awaiting! If I can make helpful changes before I start, that will be nice. I may mix and age a portion of the Tile#4 in case I want to make any adjustments: Then I can add the dry materials with a new ratio.

Midori(N), cone 10 (Japanese for green)

Custer 24
Silica (Flint) 19
Wollastonite 17
EPK 19
Crimson 5
Gersley Borate 4
Volcanic Ash 12
Mag Carb 4.5

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Ceramics by avaviel, on Flickr
This is a glaze that is like a green clear, it crazes. This is the new formula that my teacher came up with, he rearranged a few things and made it shorter. (He described it as rearanging the parts of the glaze, consolidating the fluxes and glass makers.) I'll post a photo of the glaze bowl that this is on, I think I can live with the crazing. Typically, crazing have the cracks going in many directions... but on one of my bowls with a flat edge about a centimeter across, the cracks are about a cintemeter apart, all facing to the center. It's rather stunning: and I can say that because it wasn't my conscious choice to have it to do that! This is also the glaze that taught me that making glazes is really fun.

Metal Glaze Test, cone whatever... but I'll do it in 10.

Bone Ash 10
Talc 8
Iron Oxide 10
Silica (Flint) 20
Feldspar!!!!!!!11111!!1eleveny: 48
Here is the joke, regarding the feldspar: I saw this glaze in an old magazine. (I'll get the edition number later.) I showed it to him: It was a glaze for a predominately iron matte glaze. He read through the ingredients, saying that they made clear sense until he got to the feldspar. Which feldspar was the question. To that end: Let the glaze testing commence!

In our art dept's clay area, we have four feldspars: Custer, F-4 (Soda), Sopdome, and Neph Sy. The idea is to mix the glaze around 300 grams four times, each with the full percent of the separate feldspars that we have in stock. Then, do a bunch of glaze tests to try and find something that we like. (We're not trying to duplicate the magazine, that would be futile and silly.) So there will be a bunch of test tiles with C+S+NS and so on.

Interesting links:
This is an older post about Lucy Rei's glazes. I plan to look up the magazine and post the results of the tests. Hopefully they have some of her cratering glazes.


Hey, look. Iron!

Crater/rough glaze

25 November 2012 - 11:05 AM

I'm rather fascinated with Japanese and Oriental ceramics. I've noticed a tendency for their pots that are used daily, such as teapots and tea cups without handles, to have a rough dark glaze. Edit: the inside of the cup/teapot would be food safe smooth glaze, and the outside rough.

I'm not wanting to go as far as Lucie Rie with her crater glaze, my goal is a porous soft surface that a cup can have a hot drink, without burining the person's hand.

I've read that silican carbide in tiny amounts (0.5% to 1%) can cause the bubbling. Are there any other materials that can be used to get similar results? Such as a matt surface the does not transfer heat — as if you were holding a rock. Are there any glaze recipes the are a useful starting point for my testing?

I'm looking for cone 10 glazes, but I'm sure I could modify cone 6 glazes. As for background, I'm an art student at a college, with access to glaze chemicles for making test glazes. (They let me in the glaze playground!)

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