Steven's Glazes - Tested at Cone 6

[George Lewter]

Is anyone testing some or all of Steven's cone 10 glazes at Cone 6. If so, can you let us know about the results with close up pictures and firing details?

 

So, CM?!. Can you share any details with us?  Are the glazes all formulated the same as they were in his handouts, or has he made flux adjustments for the lower firing temperatures?  What kind of firing schedule are you using?  Are you also firing the gas kiln to cone 6?

 

I asked Steven a year ago if we could publish the Glaze recipes here, but never got an answer, so we've just referred our members to Lakeside Pottery where the recipes are online, but it would be nice to have them right here. 

[Mary Jane]

Hi - Steven did mention the problem with the cone 10 b-mix at the workshop I attended as well. I have heard from other people that cone 5 b-mix tends to bloat at cones higher than 5. A friend fired a full load of cone 5 b mix to cone 6 using coyote glazes. The pieces had been bisque fired first. She had a lot of bloating but it may be that the bisque firing was too fast.

Seepage is what I call it when i take fired pieces and put water in them - let them sit - and then test for dampness on the bottom of the piece. The pieces are not really leaking, but the bottoms are wet enough to cause a problem on a table, etc. I did not glaze any of the bottoms. I am wondering if anyone else has tested these for that issue. Could be a problem for a vase, for example.

Would love to hear how the cone 6-7 firing goes.

Thx, MJ

[George Lewter]

Clarification on bloating and seepage. I have used Laguna B-mix 5 (their mid-fire formulation) for a couple of years in regular bisque - glaze - glaze fire cycles with no bloating or other body defects. I have only had body issues when I've tried to single-fire.

The issue of seepage is related to two factors that I can think of. The first is body maturing. As a body is fired to its maturing heat, it sinters and compacts and loses porosity, Underfiring a high fire body sacrifices solidity. With such a pot you would be depending entirely on the glaze to seal the body and any unglazed area or crazing of the glaze would compromise the water resistance of the more porous immature body.

[Mary Jane]

Have you been firing the cone 5 b-mix to cone 6 with a hold or just the "regular" cone 5 firing? I had been told by a few people that they had bloating when firing above cone 5.

Have you been able to do a successful cone 6 firing of Steven's glazes without modification and using the cone 5 b-mix? Did the glazes mature at this cone?

I agree that the cone 10 b-mix is not mature when fired to cone 7 with the hold, and that is the main reason for the absorption issue. As I mentioned, the coleman porcelain did not seem to have the issue when I tested. In addition, the white liner glaze seemed to adequately seal the piece. I am not aware of any readily available clay bodies that mature using the "recommended" firing schedule of Steven's, and i wondered if anyone else had problems with this "seepage" using these glazes and firing schedule with cone 10 clays. It could also be my application of the glazes.

Thanks, MJ

[George Lewter]

First of all we need to be clear that there are at least 4 different manufacturers of "B Mix" clays in the US. I found that many in a minute and a half of searching. I have no doubt that they are all variations on the theme of something intermediate between a "white" stoneware and a true porcelain. The motivation for a b-mix appears to be ease of throwing. That said, my experience is confined to Laguna's eastern plant b-mix 5. I have fired it without defects on pre bisqued pieces for about 2 years. My firings have varied from about cone 5.5 to 7.5. All of the pots shown here were in the vicinity of cone 7 (actual cones with cone 6 touching down or flatter, and cone 7 starting to bend through touching down and curling at the tip. I find no bloating in any of them.

The first and last pots were glazed with SCM, Hannah's fake ash, and possibly very slight amounts of spotted black. The middle bowl was glazed with C Harris temoku.

[Mary Jane]

Hi - the cone 5 b-mix that I was referring to is Laguna b-mix but it comes from the west coast. I have heard that there is a slight difference between east and west coast versions. That is very good to know that you were able to fire it to 7.5. So, just to clarify, did you fire to cone 7 and then hold for an hour to get the 7.5 - or is this just a glaze firing to cone 7.5 and than let the temperature drop immediately? Or, did you you fire to cone 6 and hold to get to the 7.5? When I did my firing after the workshop, I fired to cone 7 and held for an hour. My cone 8 cone was all the way down and my cone 9 cone was actually just starting to bend. Love the results that you got. I am attaching a photo of one of mine that I glazed at the workshop. I would love to be able to get a similar result firing lower. I have not gotten around to mixing up any of the glazes and probably won't until fall.

Was the middle bowl with the c. harris tenmoku fired to cone 6 in oxidation? Is the recipe available and what did you do to get the stripes? It looks like something I would get out of a cone 10 reduction kiln using rc wash for the stripes.

[George Lewter]

Hi again,
I fire to cone 6 in a manual kiln sitter equipped kiln. When the sitter trips off, I restart and try to maintain the same temperature for 30-60 minutes. Until recently I was getting about two cones of variation between the top and bottom of my kiln. The addition of some fiber insullation on top of my kiln and refinements to my vent system have cut the differential to about 1/2 to 1 cone, so I now end up at about 6.5 to 7.5 throughout the kiln. I downfire slowly for mattes. My cooling cycle depends on what glazes are in the load. For Steven Hill glazes I try to stay under 80 deg F/hr down to 1800 to allow crystal growth. Glossy glazes can cool much faster unless I want complex mixing. The C Harris Temoku and my floating red benefit from a fast cool with a 1 hr hold at 1742 deg F then turn off the kiln. The C Harris recipe is posted several places on this web site. Just use the search box up in the top header on the right of this page. There is an extensive discussion of this glaze under the teadust glaze discussion even though it is not a teadust glaze. The glaze technique was to dip the bowl in the temoku, pour out the excess glaze, and immediately squirt on Waxy White from a nozzled squeeze bottle.

Recipe Name: Waxy White - High Calcium Matte

Cone: 6 Color: white
Firing: Oxidation Surface: Semiglossy

Amount Ingredient
37.2 Wollastonite
23.5 Silica
14.9 Kaolin--EPK
14.5 Nepheline Syenite
9.9 Gerstley Borate--1999

100 Total

Additives
5 Zircopax Plus

Unity Oxide
.08 Na2O
.021 K2O
.04 MgO
.859 CaO
1.000 Total

.277 Al2O3
.1 B2O3
.005 Fe2O3

2.751 SiO2
.002 TiO2
0 P2O5

9.9 Ratio
6.8 Exp

Comments: Very nice semi-matte white on white stoneware. On Laguna 80 it tended to go clear gloss where thin (possibly fluxing iron from body, or overfired on test to or near ^7. Most reliable liner glaze as of 4/09.
-----------------------------------
Calculations by GlazeMaster™
www.masteringglazes.com
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[Mary Jane]

Hi again - Thanks so much for the information. I emailed Laguna and they say the east and west formula for b-mix is the same. They said that it is vitreous at cone 5 and more vitreous at cone 6. They suspect bloating would be due to a firing that was too fast. They mentioned that above 6 there would likely be some slumping and deforming of the piece. Curious to know if you experienced that. Based on what i saw of your pieces, they don't look as though slumping was a problem. Obviously I have some experimenting to do on this. Thx, MJ

[Teresa Wooden]

Steven is currently working with his glazes at cone six...recent experiments have proven very promising, he tells me. Watch out for eventual crazing on the white salt liner (he is not using anymore) and Pier Black (the crazing is very tight and best seen after wetting the surface and watching as it dries).

[Mary Jane]

Hi Teresa - is the white salt liner the same as the satin white liner? I took one of Steven's workshop and we got a recipe for a white liner and the pier black. Are they having problems only at cone 6 or are they having problems using the recommended firing schedule he provided at the workshop (i.e. firing to cone 7 with a hold and slow cool)? Thanks for the information. Looking forward to updates on the cone 6 issues. MJ

[Teresa Wooden]

The white liner is probably the same...the one he was using about six months ago? Fired to his workshop firing schedule. After that he developed a white liner based on a glaze that I shared with him that my husband tweaked (around April of this year). I think he's using that one now, and I've been using it too. Very well-behaved satin white. If your recipe is older than April 2010, I'll have to check with him before sharing it.

[Mary Jane]

Hi Teresa - Just checked my notes and the description is satin white number 3. The workshop was in May but I think the handout is from earlier workshops. Could you check about sharing the recipe? Thx, MJ

[CM Partin]

Hi, I'll post here too. I am Steven's resident artist and we are now totally firing at cone 6, beautiful crystals, beautiful rich colors. Mission successful. All the testing was worth it.