Tag: ceramic

Fiske ^6 Celadon

Fiske Celadon Blue
Gin&Tonic Cocktail Glasses

 

I get asked a lot about this recipe, and for good reason. It’s pretty indistinguishable from the best cone 10 recipes out there. For those purists out there, I’m referring to Pinnell Clear, Deller Chun, Cushing’s LungChun, and any number of Robert Tichane’s recipes from his book Celadon Blues. In any event, I often point people to an older post, but in the years since I mistakenly transcribed a recipe wrong and happened on the winning formula, I’ve learned quite a bit working with this glaze; Things like it working reasonably well in soda and atmospheric kilns, looking very nice from a range of cone 5 to cone 12, and readily taking most mason stains.

The Recipe

Fiske 6/10 Clear Base:

F4 (Or MinSpar) Feldspar 34.9

Whiting 12.8

Zinc Oxide 11

OM4 Ball Clay 13.8

Silica 27.5

(Pictured: Add 1.75% Robin’s Egg Blue Mason Stain)

 

Notes on materials, mixing, and application:

Feldspar:Since F4 is no longer widely available, Minspar 200 will work. Custer works as well, but the bubble matrix that really gives this glaze it’s character is different with custer, g200 (now g200hp), or nepheline syenite. Experiment first, because milage may vary. Of the ingredients, this is probably the 3rd most important.

Fluxes: Whiting and Zinc. This glaze is not kind to kiln elements. (See my post on zinc for clarification!) It’s my opinion that the relatively high % of zinc is caustic to electric kiln elements. If you must, ventilate the kiln, but expect a short life on the elements. Sometime in the near future I’ll be eliminating zinc and trying to use a frit to solve this, but until then I can only recommend firing in a gas kiln. It’s the cost of firing.

Clay: Probably the most important element of this recipe. When I was testing for cone 6 glazes, I made a mistake transcribing to a batch recipe. The result was that I had doubled the clay. After the firing I went back over the notes and realized why the glaze looked the way it did. One of the side effects of the higher clay content is that application is sometimes difficult. The higher % of clay makes thick applications crawl. To get around this I calcine 10 of the 15%.

Thus, my recipe looks like this:

Fiske 6/10 Clear Base: Minspar200 Feldspar 38, Whiting 14, Zinc Oxide 12, Calcined OM4 Ball Clay 10, OM4 Ball Clay 5, Silica 30. [H20 60%]

Silica: I use 200mesh sil-co-sil. I’ve tried 325 mesh, but it didn’t look right.

Colors/Mason Stains: I use Robin’s Egg Blue, Bermuda Green, and Canary yellow. Most colors I’ve tested, and usually 1.5-3% is pretty nice, but some take as much as 5-10%. I haven’t had much luck with purples, Pinks, and oranges, (they don’t play nice with the zinc) but honestly I’m largely done tweaking this one and haven’t tried in earnest to figure out those other colors.   Metallic oxides will also work, cobalt at like .3% for a not overpowered blue color.

Application: Can’t stress this enough. It’s gotta be thick. I tell people to glaze “Thicker than you think thick is, and then just a little thicker.” I’ve taken to adding just a touch of deflocculent to the glaze batch so that it needs less water to become liquid. I then add a bit of Epsom salt to thicken the batch up. Again, this is to taste. Dipping is absolutely the way to go with this one, but I’ve gotten accustomed to spraying it. Usually takes about 15 minutes to spray glaze something appropriately.

Firing: As I mentioned earlier, it’s got a pretty wide range. It will be fully melted, albeit slightly pin holed at cone 5. Ideally, I like to go to a perfect 6, but taking it to 7 or programming a hold in the schedule makes for some nice movement that suits carving and texture very well. Most of my work is completely smooth, so I prefer it to stay thick and not run down too much. It takes some getting used to, but when you do, it behaves very predictably. It can also go into reduction, but the colors change quite a bit. Less change with Bermuda Green, but quite a bit with the Robin Egg Blue. Its been fired every which way, and needs to be tested before full comittment.

Telluride via Moab

Jeepster parked next to a clay bank with Mount Telluride in the background.
Jeepster parked next to a clay bank with Mount Telluride in the background.

 

 Back in the studio after a great trip over to Telluride, CO via Moab, UT. You better believe I scooped up some of this clay, ball-milled it, and made a slip. I also packed the jeep with a load of rocks and shit.  More on that as the story develops!

 

Red Siltstone and Clay, Telluride, CO
Red Siltstone and Clay, Telluride, CO
The San Juan Rocky Mountains.
The San Juan Rocky Mountains.
Moab Red Rocks
Moab Red Rocks

New Pots, New Recipes

#6, #5, #4 Manganese Saturate Crystalline Glazes
#6, #5, #4
Manganese Saturate Crystalline Glazes

#4 Recipe & Schedule

Fisker Bronze
Custer Feldspar.............     57.000  
  Alberta Slip................    7.000  
  Sil-co-sil..................    2.500  
  F-4 Feldspar................    1.500  
  Calcium Carbonate...........    0.500  
  Dolomite....................    0.500  
  OM #4 Ball Clay.............    2.000  
  MnO.........................   23.000  
  Copper Carbonate............    5.500  
  Iron Oxide Red..............    0.500  
                              =========
                                100.000

  Oxide   Formula  Analysis    Molar%
  CaO      0.043*   1.129%w   1.376%m
  MgO      0.019*   0.348%w   0.590%m
  K2O      0.143*   6.237%w   4.528%m
  Na2O     0.071*   2.052%w   2.264%m
  P2O5     0.000*   0.007%w   0.003%m
  TiO2     0.001    0.055%w   0.047%m
  Al2O3    0.252   11.952%w   8.013%m
  SiO2     1.783   49.756%w  56.619%m
  CuO      0.099    3.670%w   3.156%m
  Fe2O3    0.013    0.955%w   0.408%m
  MnO      0.724*  23.839%w  22.995%m

                        Cost:   0.273
              Calculated LOI:   3.521
                 Imposed LOI:        
                       Si:Al:   7.066
                      SiB:Al:   7.066
           Thermal Expansion:   6.848

Fired in Blaauw Reduction Schedule (in Celcius):

time_temp 00:00 5
time_temp 00:54 140
time_temp 01:12 260
time_temp 01:10 550
time_temp 00:30 600
time_temp 01:12 900
oxidation 83
time_temp 00:45 900
oxidation 93
time_temp 03:06 1210
oxidation 98
time_temp 01:24 1270
cooling
time_temp 02:15 1000
time_temp 01:00 900
time_temp 02:00 500
time_temp 01:00 300
time_temp 02:30 50
time_temp 04:00 50

#5 Recipe & Schedule

  Nepheline Syenite...........   65.500  
  MnO.........................   22.000  
  Silica......................   12.500  
                              =========
                                100.000

  Oxide   Formula  Analysis    Molar%
  CaO      0.018*   0.465%w   0.559%m
  MgO      0.004*   0.067%w   0.112%m
  K2O      0.071*   3.036%w   2.175%m
  Na2O     0.228*   6.461%w   7.033%m
  Al2O3    0.330   15.361%w  10.163%m
  SiO2     1.913   52.523%w  58.975%m
  Fe2O3    0.001    0.072%w   0.030%m
  MnO      0.680*  22.014%w  20.953%m

                        Cost:   0.312
              Calculated LOI:   0.065
                 Imposed LOI:        
                       Si:Al:   5.803
                      SiB:Al:   5.803
           Thermal Expansion:   7.492
              Formula Weight: 218.874

Strike Reduction Hold Firing Schedule 
in Small Test Gas Kiln in F

3:30 -> 1500F (^012)
Body Reduction
1:00 -> 1700F (^04)
Adjust to Moderate reduction, fast climb
3:30 -> 2300F (^9 flat, ^10 down)
Crash Cool
0:15 -> 1840F
Cut secondary air, minimize primary air, damp in, gas low to strong reduction and stalled holding temp
3:00 -> 1840F (Hold)
Off, Natural Cool
6:00 -> 300F

#6 Recipe & Firing Schedule

  Custer Feldspar.............   69.000  
  OM #4 Ball Clay.............    1.500  
  MnO.........................   27.500  
  Granular Manganese..........    2.000  
                              =========
                                100.000

  Oxide   Formula  Analysis    Molar%
  CaO      0.007*   0.210%w   0.256%m
  MgO      0.000*   0.006%w   0.010%m
  K2O      0.140*   6.961%w   5.057%m
  Na2O     0.064*   2.091%w   2.308%m
  TiO2     0.000    0.018%w   0.016%m
  Al2O3    0.226   12.223%w   8.201%m
  SiO2     1.533   48.751%w  55.512%m
  Fe2O3    0.001    0.123%w   0.053%m
  MnO      0.789*  29.617%w  28.588%m

                        Cost:   0.297
              Calculated LOI:        
                 Imposed LOI:        
                       Si:Al:   6.769
                      SiB:Al:   6.769
           Thermal Expansion:   7.120

Fired in Blaauw Reduction Schedule (in Celcius):

time_temp 00:00 5
time_temp 00:54 140
time_temp 01:12 260
time_temp 01:10 550
time_temp 00:30 600
time_temp 01:12 900
oxidation 83
time_temp 00:45 900
oxidation 93
time_temp 03:06 1210
oxidation 98
time_temp 01:24 1270
cooling
time_temp 02:15 1000
time_temp 01:00 900
time_temp 02:00 500
time_temp 01:00 300
time_temp 02:30 50
time_temp 04:00 50

Raw Materials in Cone 10 Reduction

From Utah State University Ceramics Technology Glaze Calculation Class.

Thanks to Shasta Kruger for Photographing, Editing, and Compiling These Images!!!!