So, is anyone ready to dive into single firing? I have some bone dry test tiles I'm going to try out with a couple of my glazes that I know shrink a lot on bisqueware. I have a Ron Roy black that I think might make a good raw glaze for dipping to glaze greenware. I'm going to make some small bowls with grippable feet, that I can hang onto when I dip them. I'll try glazing some at leather hard, some at bone dry, and on the last batch, also bone dry, I'll wax the feet and spray them. Hopefully, I can have them done in a week. We learned that waxing the feet is pretty necessary when spraying greenware. The glaze gets under the pot, and if you haven't waxed, when you wipe off the excess glaze, you'll also be wiping away the clay!

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Still going to fire to ^6? And instead of spraying, could you lightly brush it on? (don't have spray equip.)
Brushing should work much better than on bisqueware, but you will need to experiment with how thick to apply and if you need to let it dry between coats. I'd try it both leather hard and bone dry. Adding too much water can cause raw pieces to disintigrate, so experiment on pots you don't love.
I just watched a short video by Simon leach on you tube. He demonstrated waxing a slip decoration he had applied to a dry raw clay pot. Then he went on to dip glazing the same pot. One of the things he mentioned was that it was important to glaze the inside and outside within a short time span or you would end up with cracks in the pot due to uneven moisture content from one side to the other. That makes sense to me. On the other hand if that were the case wouldn't the wax cause the same problem blocking the moisture?
I think doing inside and outside at nearly the same time would be more important on bone-dry ware than on leather hard pieces. On leather hard pots there's a lot of moisture in the pots so your getting less extreme variations from wet surface to dry clay body to wet surface.
I always fire cone 6 in my studio and recommend we all do as much as possible. This will make sharing glazes and techniques much more useful. And yes I will use brushed-on glaze on a few pots as well as dipping and spraying. We should all try all techniques to verify what what we're learning.

This is a clear single fire base glaze from clayart.
Potash Feldspar 38
Flint (Quartz) 20
Whiting (Chalk) 32
Ball Clay 10
Bentonite 2
Can be applied thick, takes oxides well, very stable over a wide range, does not run. If this one works for you let me know. It really is a stallwart for me.If you give it a really good cone 6 -7 then it will pool nicely. Happy potting Marek
I threw 4 small bowls this evening for my first try at raw glazing and single firing. I'm hoping my feet are projecting enough that I can hang on to them when I do dipping. Anyone else got any pieces in process?
Tonight I raw glazed 3 leather hard pots. I was testing with GA25 Black which I believe is a Ron Roy recipe from Mastering Cone 6 Glazes. I chose this glaze because it tends to shrink and crack on my bisque pots if even slightly thick. For raw glazing I wanted the glaze thicker than normal, so I poured off the water at the top of the glaze bucket before stirring the glaze. Otherwise it was just my regula glossy black glaze. The first bowl had a tear at the rim, and I thought it might be interesting to finish. I poured the interior and turned it upside down and dipped the exterior. It wasn't long before I noticed a vertical crack forming at the bottom of the tear. The rim was very thin there, compared to the rest of the rim so the expansion caused by the pot absorbing glaze pullted it apart at this weak point. Otherwise the glaze application looked good.

The next bowl had a split rim. I filled the groove with a sky blue glaze, and then poured/dipped the bowl the same as the previous bowl. I didn't have any problem with this bowl.

The third bowl I glazed by brushing with the same black, horizontally around the interior then vertically, then the same two coats around the outside. I added a coat of Storer Semi matte green around the upper outside surface and allowed some drips to flow down the exterior.

The three pots are drying. I will inspect them before and after firing them in a week or so.
First setback noticed 9/19/09 - Glaze flaking off unfired rims and exteriors of both the dipped and the brushed pots (if this happened in firing it would be called shivering). Interiors did not seem to be affected. Attributable to clay body continuing to shrink after the glaze has more or less stabilized.

The pots are all dry. I peeled off the loose glaze and touched them up with a brush. I mixed up a batch of Richard Busch's nutmeg glaze and applied it to four tumblers accented with Ron Roy GA25 black. (Both glazes have high caly content so might work for single firing. There are other raw pots with black and waxwing brown also ready to go. I packed everything in along with some test tiles and started the kiln preheating as the freshly glazed stuff is pretty moist. Depending on the temperature when I wake up, I may either mix up a few more test glazes to throw in or turn that baby up to burn. I really need a test kiln. It's 4:30 a.m. and I'm a little punchy. Goodnight all.
At 11:30 a.m. the kiln was up to about 300 degrees so I turned it up and began firing in earnest
1 a.m. Kiln shut down. Will post results and pix tomorrow evening.
My results were not perfect, but they were very encouraging. The pots I glazed leather hard, developed shivering problems before the firing and the repairs I attempted did not resolve all the problems. The black glaze (GA25 Ron Roy Black) popped off in places and melted into the interiors and left a few bare spots on the exteriors. The one that I brushed on did not have enough coverage to cover the white clay body.

I got much better results with the pots I glazed at the bone dry stage. One of the three base glazes Waxwing Brown tends to bloat if at all over fired, and this happened on two cups I used it on, in combination with the black. This was not a single firing issue.

I did get very pleasing results with Richard Busch Nutmeg and black on three tall tumblers.

I didn't note any defects in any of the three.



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