SHAMBHALA POTTERY
C10R TEST TILES CHUN GLAZES
GROUP 1
I had some difficulty scanning this group of tiles and couldn't get a clean scan, without the glare on some of the tiles. Just know that those light glares are not part of the glaze surface.
These glazes were all fired to Cone 10 in a Geil, gas kiln. Chuns need reduction to develop the rich colors seen in some of the tiles. Usually, the more reduction, the deeper the color. Also, the colors will be quite different, showing more and deeper color on iron bearing bodies.
Chuns can be the most beautiful and sometimes the most challenging of glazes. They seem to show their greatest beauty, just before they are ready to run off the pot on their way to the kiln shelf! ! They can be prone to pinholing as well. Give them a nice, slow ,reducing fire and a long time between the last couple of cones to give time for the pinholes to settle down. Fast firing just causes these glaze to boil fiercely, increasing your chances of pinholes.
Fire your bisque slowly to C04, particularly if you are using an iron bearing stoneware. The slow bisque will help release carbon and help to keep the pinholing down.
I liked to reduce lightly early because I was usually firing shinos and other glazes which develop better color with early reduction. These chun glazes melt early, so I have always reduced them early, but not too heavily until later in the firing. In fact, periods of light reduction or neutral atmosphere, alternating with heavier reduction will often give brighter glazes. I find this to be particularly true of celadons.
SUGGESTION: When testing these glazes, try to use a white or porcelain engobe on one half of an iron bearing test tile, or a low iron slip on a porcelain or white stoneware test tile. This will give you a broader view of the color range of these glazes. Put the slip on the front and back to maximize the information you can garner.
June Perry
RECIPES
Top left tile is #1081 on Los Altos, an iron bearing stoneware. It's a nice strong chun blue on this body; but the glaze crazed . It might behave better with washed ash. I believe I used pine ash for this test.
Custer feldspar 16
Volcanic Ash 47
Silica 15
Whiting 13
Soft wood ash 9
ADD: Yellow Ochre 2.5%
Top row, second tile from left is #6601 Color B June Perry Chun on Tom Turner porcelain. It's a bit over fired at a flat Cone 10. I would probably add a bit more clay and silica to this for future use. I also think the color would be better either over a low iron slip (1-2%) or on an iron bearing body, although it looks like it would be a good, delicate blend of colors if it hadn't moved so much.
Ferro Frit 3134 10.72
Barium Carbonate 4.09
Dolomite 9.65
Whiting 5.49
Zinc Oxide 1.56
G200 Feldspar 31.44
EPK 7.02
Silica 27.59
Tin Oxide 2.44
ADD: Rutile 4%, Yellow Ochre 3.5%
Top row, third tile from the left is #313 on a white body (not sure which) Shows some glaze rolls at bottom at full Cone 10. Would probably be better, as the previous glaze, somewhere between cone 10 starting to cone 10 at about 2-3 o'clock. (This may be an error. The tile is very clearly marked but the glaze in my book says Yellow Semi-Matt) I'll put the recipe here because it may be correct. There's vanadium in here and that can gives blues. I hope its right because this is a very nice glaze!
This glaze has a range from C8-10. It's a semi matt at cone 8 and a gloss at Cone 10.
Custer Feldspar 38.3
Whiting 18.7
Barium Carbonate 9.0
Custer Feldspar 38.3
EPK 8.0
Silica 26.0
ADD: Red Iron Oxide 2%, Vanadium Pentoxide 5%
Top row far right tile is #332 Chun blue, on an iron bearing body.
Barium Carbonate 4.6
Colemanite 9.1
Dolomite 9.1
Whiting 2.7
Zinc Oxide 1.8
Kingman Feldspar 43.8
Kaolin 1.5
Silica 27.4
Add: Zircopax 0.6%, Copper Carbonate 0.5%, Rutile 5.2%
Second row from the top, far left tile is #1026 Schacter Blue Purple on Tom Turner porcelain. It's a nice, delicate light blue with light tan, variegated glaze. It would be deeper and richer in color on an iron bearing body or over an iron slip.
Barium Carbonate 4.5
Dolomite 9.0
Gerstley borate 9.0
Whiting 2.7
Zinc Oxide 1.7
Custer Feldspar 21.6
Kona F4 Sodaspar 21.6
EPK 1.9
Silica 28.0
ADD: Tin oxide 2.7%, Copper Carbonate 0.5%, Red Iron Oxide 1%, Bentonite 2.1%
Second row from the top, second tile from the left is #1210 Color A on Glazier, a white stoneware. It's a nice C9-10 rutile blue with lots of pink. Like some of the others, it shows some glaze rolling at the base and would probably be better fired to C10 starting. This base is also good for copper reds. If I have some tiles I post them on the copper red page.
Custer Feldspar 42.1 (I did a G200 spar test but it was better with the Custer)
Silica 27.2
Colemanite 8.8
Dolomite 8.8
Barium Carbonate 4.4
Tin oxide 2.6
Whiting 2.6
Kaolin 1.8
Zinc Oxide 1.7
Color A, ADD: Rutile 3.2%, powdered illmenite 2%
Second row from the top, third tile from the left is #6601 Color C June Perry Chun on Tom Coleman Porcelain. It is a pale textured powdered blue with lighter variegations. (See base recipe above)
Color C, Add: Copper Carbonate 0.5%, Rutile 5.6%, Cobalt Carbonate 0.2%
Second row far right is also #1210 Color A on an iron bearing body. See above for the recipe. This test is lighter than the one on the Glazier body and I think it may not have had as much reduction. Either that or there is an error in the naming of the tile.
Third row down, first tile from the left is #1239 Shrope Blue, on Sasuga Porcelain. It's a nice smooth, glossy glaze with lots of variegation of color from light blue to pale pink to off white.
Dolomite 15.8
Custer Feldspar 30.0
Whiting 11.1
EPK 16.8
Silica 26.3
ADD: Rutile 8%
Third row down, second tile from the left is # 1210 Color A on Kai Porcelain. See above for recipe. Notice the difference in color in this same recipe on various bodies. This is a lovely light blue, with pink, smooth glaze.
Third row down, third tile from the left is #332 on Amador, an iron bearing stoneware. The clay doesn't show heavy body reduction and if it did, the color would be deeper. The lighter color of top is where it was double dipped. The glaze is better with a single dip. It's a very nice chun if applied at the right thickness. See above for recipe.
Third row down, far right tile is #2450 Color B June Perry on an iron bearing body (looks like Rods Body). This is a richly colored rutile glaze with blue and rust. This one worked well at a full cone 10.
Custer Feldspar 53.60
Whiting 12.80
Barium Sulfate 2.96
EPK 5.90
Zinc Oxide 2.44
Silica 22.30
Color B, ADD: Rutile 4%, Yellow Ochre 3.5% Tin Oxide 3.5%
Bottom row, far left tile is #1690 Color A June Perry (on porcelain or white porcelain type stoneware). This glaze is a rich eggplant color with some light butterscotch color as well.
Custer Feldspar 39.83
Whiting 17.06
Kentucky OM4 Ball Clay 14.58
Silica 28.53
Color A, ADD: Rutile 3%, Powdered Illmenite 2%.
Bottom right, second tile from left is #6670 Revised Color A June Perry Chun on Tom Turner porcelain. The glaze is smooth, with a light beige color with some light blue. The amount of rutile is low and it may have needed more reduction, or additional rutile to get more color on a white body. It would definitely have more color on an iron bearing body or over an iron slip. The first test I did crazed so I revised the recipe. I'm assuming the tile is the revised version since there is no crazing showing!
Barium Carbonate 3.68
Dolomite 7.87
Whiting 4.10
Zinc Oxide 1.34
Kingman Feldspar 27.23
Grolleg Kaolin 7.85
Silica 31.27
Tin Oxide 1.77
Ferro Frit 3134 4.96
Ferro Frit 3195 10.74
Color A, ADD: 3% Rutile, 0.54% Tin oxide (this is in addition to the tin in the base recipe).
Bottom right, third tile from the left is #1210 Color B on Rods Body, an iron bearing stoneware. This glaze has a very interesting color on this type of body, particularly when applied a little thinner. See above for base recipe.
Color B, ADD: 6% Rutile
Bottom row, far right tile is #1034 Color B on Windsor porcelain. I love this glaze. It's pinkish, light blue, with lovely variegations. On an iron bearing body, is a darker blue. This is a Carlton Ball recipe.
Barium Carbonate 4.2
Dolomite 8.4
Gerstley Borate 8.4
Whiting 7.2
Zinc Oxide 1.6
Custer Feldspar 40.1
Kaolin 1.7
Silica 25.9
Tin Oxide 2.5
Color B, ADD: 4% Rutile, 3.5% Yellow Ochre
Email: ShambhalaPottery@frontier.com
