Line Blend Glaze Testing

     In glaze testing, sometimes finding a color or glaze surface you like can be a challenge. Line Blending, with all its variables, can assist in making it less so. Line Blending is basically a way to gradually change variables in a glaze recipe. The most simple line blend is a Single Variable Line Blend:

     In a Single Variable Line Blend you increase the percentage of something in addition to the 100% recipe. This makes Single Variable Line Blends incredibly helpful in finding the right amount of colorant or opacifier you'd like in a glaze. The numbers at the top of each figure is the number of each tile. For this type of line blend, A represents a base glaze and B represents an additive. Taking a clear glaze and adding percentages of Red Iron Oxide, for example, could take you from a celadon to an amber to a Tenmoku (However I'd increase the percentages by .5% instead of 1%). The percentages show above are just listen to illustrate the idea, but you can change the increments between each tile by any amount. 

     The easiest way I've found to do this type of line blend, rather than mix up seven separate glaze slops, is to mix a 500 gram batch of the base and dip tile 1, then add 1% of the additive and dip tile 2, add another 1% of the additive and dip tile 3, and so on until finished. Obviously, this is not exact because you take away some of the base with each dip, but its close enough to get you in the right area for the color you're looking for.

     The next form of Line blend is a Double Variable Line Blend. This line blend is good for mixing two additives (Copper Carbonate and Tin Oxide for example) to find the right mix of both. This type of line blend, as well as all of the following line blends are completed using a much different process than a Single Variable Line Blend. For this, and all of the following blends, you mix up a glaze slop of the base for each letter. Then in each glaze slop you add whatever you'd like to be blending. The more tiles you will be dipping the larger of a glaze batch you'll need to make. 

     For example, you could have two 500 gram batches of:

Custer Feldspar - 34

EPK - 33

Whiting - 33

    In one batch you add 5% Red Iron Oxide (which would be 25 grams) and in the other you add 10% Titanium Dioxide (which would be 50 grams). Then you use a spoon to take the proportion of each batch into the mix - Tile 5 for example would be two spoonfuls of batch A and four spoonfuls of batch B. This is demonstrated in the image below. Thoroughly stir the mix and dip your tile.

  

   To calculate the recipe of a single tile, follow the image below.

     The following types of line blending are all complete the same way as Double Variable Line blends, however they require increased amounts of glaze slops (Biaxial and Triaxial require three, and hexaxial requires six).

     The Hexaxial Line Blend is a beast of my making. If you're looking for a specific glaze base you can put one material on each corner and blend them to find 37 different bases. Most of them might not work, but this allows you to see lots of different bases all at once. It also works just like any other line blend and you can have one base with 6 different additives.
     The reason the tiles skip numbers unlike the previous line blends is that it would require an enormous amount of tiles to make it have smaller increments, but line blending is a general experiment anyway. As you do line blends and become more particular with what you're looking for you can hone in on the area of a line blend you like the most.

     If you have questions please feel free to ask, and if you have tested any of these (especially the Hexaxial) and would like to share please do!

Shino Glazes

     Shinos are one of my favorite types of glazes, if not my most favorite. They are incredibly variable and incredibly cheap. There's no need for expensive colorants - let alone any colorants for that matter - to make interesting colors in the glaze. That's not to say that colorant's can't be added, but there really isn't any need. With just various mixes of the basic ingredients that make up a shino (clay and feldspar at the most simplistic level) colors like tan, orange, red, gray, black, and gold can be achieved. And, they don't run so there isn't any worry for your shelves.
     There are a few types of shinos: Traditional, Carbon Trapping, Red, and High Alumina (or white, very similar to traditional but with more alumina). I don't have a personal High Alumina glaze, but these are my Traditional, Red, and Carbon Trap shinos:

Carbon Trap Shino

Neph Sye - 45
Spodumene - 15
OM4 - 15
F-4 Feldspar - 10
Redart - 5
Soda Ash - 18

Traditional Shino

Neph Sye - 70
Fire Clay - 30

Red Shino

Neph Sye - 20
EPK - 20
OM4 - 20
Soda Ash - 20
Spodumene -20

      A common shino idea is that you can mix 70% - 80% of Neph Sye with 20% - 30% of pretty much any clay to get a shino, and that's all my traditional shino is. There's no need to hunt down any Fire Clay to make one, just use OM4 or EPK. Really, any clay could work. Even XX Saggar - as seen below.
     I personally am a fan of Carbon Trap Shinos the most, so I experimented more on mine. Additions of various ingredients and substitutions of others have interesting effects.

Carbon Trap + 1% Rutile

Carbon Trap + 3% Rutile

Carbon Trap + 2% Rutile

Carbon Trap with 5 grams
extra Redard added

Carbon Trap with XX Saggar
substituted for OM4

Carbon Trap with Salt
substituted for Soda Ash

     Sodium is what captures the carbon in Carbon Trap shino's giving that nice gray - black speckling. Therefore, just about any high sodium material can be added in an attempt to trap carbon. Using wax resist right after glaze application will prevent sodium build up and show a wonderful effect of different colors in the glaze due to carbon trapping and fluxing. Substitutions like salt work well.
     Now, my Carbon Trap Shino already has a nice metalic lustrous shine, but with additions of Rutile increase that golden shine. Interestingly enough though, from 1, 2, and 3 percent the color changes from brown/gray to blue/black, to gold respectively.

     However, there are some important things to know about shinos:

• Because they have such high clay content they generally have a higher melting point that other glazes. This means that other glazes should generally be layered on top of them if you layer glazes. That's not to say that some artists have success disregarding this, because some do.  
• Iron Oxide washes painted on top of a shino will go gun metal and run.
• The crazed surface in high sodium shinos will bed bacteria just like other crazed surfaces.
• Shinos are fired in reduction, and the Carbon Trapping shinos like heavy reduction firing.

Copper, Iron, and Rutile Line Blends

        These line blends show the effects of Copper Carb, Iron Oxide, and Rutile on the Permafrost base as well as the effects of Copper Carb on the Shorn Base. The increments of each line blend consisted of 1% - 5% regardless of colorant or base glaze. 

                   Permafrost Base                                         Shorn Base

                       Neph Sye - 45                                       Wollastonite - 25

                           Flint - 30                                            Spodumene - 25

                         Whiting - 8                                        Cornwall Stone - 25

                       Dolomite - 10                                            Talc - 25

                           Talc - 7

Permafrost Base, Copper Carb Line Blend

      Copper Carb does not flux the Permafrost Base to a noticeable amount, however increased amounts of Copper Carb begin to form very small crystals that sparkle on the satin glaze surface.

Permafrost Base, Red Iron Oxide Line Blend

      The Permafrost Base becomes more and more runny and glossy as higher amounts of fluxing agents are added, such as Red Iron Oxide. The two tiles furthest to the right were so fluid that they ran off the tile.

Permafrost Base, Rutile Line Blend

         Rutile, like Red Iron Oxide, fluxes the Permafrost Base in higher amounts. At 3% the Rutile begins to noticeably crystalize on the surface of the glaze. By 5% it fluxes the glaze enough to add a Hare's Fur like effect.

Shorn Base, Copper Carb Line Blend

     The Shorn Base alone is very runnny, so the effect of any fluxing that the Copper Carb might have caused is not noticeable. Increased amounts do, however, change both the color of the crystals and the glaze matrix. Higher amounts of Copper Carb deepen the teal background and make the crystals gunmetal.