General information Coyote

Developed by experienced potter Martin Butt, Coyote glazes are currently the best commercially produced finishes available to ceramic artists working on cone6. Founded as a pottery school in 1996, Coyote originally sold glazes primarily to former students who lacked the time or material space to make their own glazes. Since then, Coyote Clay and Color has become one of the most well-known glazes in the world. The best-known manufacturers ofcone6 glazes. All Coyote glazes are designed to be used directly from the pot. Every batch of Coyote glaze is test-fired before it is sold, ensuring that each color meets our rigorous standards. New glazes are still tested by students from the original school before they are released, so even the newest Coyote colors have hundreds of hours of testing behind them before they hit the market! Coyote glazes can be brushed (we recommend three coats, alternating the direction of your strokes with each coat).

Application of glaze

Coyote glazes must be applied to cookie. The trick to glazing is to get an even application of the right thickness. Too thin and the colors can get ugly, too thick they can run out. We always clean our cookie with a damp sponge or quickly wash it off under the tap just before glazing, as the dust will wash off the glaze and the glaze brush will adhere better. Just before using, mix the glaze thoroughly. A soft, full brush works best for the glaze, we prefer a 1″ or 2″ wide brush; it holds a lot of glaze, and gives a nice even layer thickness. It is easier to get even coverage if you alternate the direction of your brush strokes: brush the first layer from side to side, then the next layer up and down. Let each layer dry completely before applying the next. It is important to remember that every brush and glaze is different. Most colors should look best after 2-3 coats, but you should make several samples when trying a new color or combination to find the thickness that works best for you. Leave about 1/4″ at the base unglazed. All glazes can move/sag a bit to the bottom of your work. Some combinations are quite runny (see list below for runny glazes). Always leave enough room for your glaze to flow a bit without it staying on the kiln plate. Until you are familiar with a particular glaze, it is best to leave some extra space. Make sure there is no glaze on the bottom of your piece; Glazes are melted glass in the oven, so if there is glaze on the bottom, or if it is too thick and runs, your pot will stick to the plate. This will break your pot and your kiln plates. If glaze has gotten on the bottom of your piece, just wipe it clean with a damp sponge.

Firing

Each kiln and firing is different. It is best to use witness cones with each firing. Coyote glazes are designed to be fired between cone 5 and cone 6. This is between 1180 and 1220 degrees. Most digitally controlled kilns have a pre-programmed cone firing setting that allows you to achieve the correct temperature with a minimum of fuss (we use a cone5, fast, with 30 minute commute.) For manual (sitter) kilns, we recommend using a cone6.

Slow Cool Heating Program

Slow cooling glazes can give very different results at different firing curves. Many Coyote glazes are specially designed to take advantage of this to create special effects, and many more glazes are affected in surprising ways. All Coyote glazes can be slow cooled. Slow cooling effectively extends the firing period, during which most crystals develop, resulting in more and larger crystals. Depending on the composition of the glaze, this will usually produce large visible crystals, or a matted surface (microcrystals). To slowly cool a glaze, bake in an oven with a digital controller. Since the control panels of programmable ovens vary from brand to brand, you should consult your oven’s owner’s manual or contact the seller or manufacturer of the oven for instructions on programming your particular oven. Once you know how to program your kiln, it is a matter of experimentation to find the firing cycle that works best for your own kiln and glaze combinations. The only way to make sure your kiln is firing correctly is to use witness cones. As a starting point, our chart below is what you can use as a guide for your own slow firing program: 0 – 105°C in 2.5 hours 105°C – 1095°C in 5.5 hours 1095°C – 1205°C IN 0.5 hours + 15 minutes shuttling 1205°C – 1176°C in 0.5 hours + 15 minutes shuttling 1176°C – 760°C in 8 hours allow to cool further below 50°C. It is important to note that you must adapt this schedule for your own furnace and fires. Every kiln is different, so there is no schedule that will work for every firing. Testing is very important here to get the right crystals.

Food Safety

Currently, the only materials regulated by the FDA regarding food safety in ceramic glazes are lead and cadmium. All Coyote glazes are lead-free, and the glazes containing cadmium (in the form of inclusion stains) have met FDA guidelines for cadmium release in our tests when properly fired. Because of the many variables in each studio, we cannot guarantee that your items will be safe for food use. Firing temperature, interaction between different glazes or possible contamination can all affect the food safety of your work. Potters making items for food use should test their own work to determine the status of the service. We recommend that the potter test items produced for sale in an accredited laboratory before marketing them. Brick Red, Buttercup, Butterscotch Shino, Cedar Shino, Cherry Satin, Coral Satin, Dusty Rose, Fire Opal, Lemon Cream Satin, Orange, Peach Blush, Plum Shino, Pumpkin, Really Red, Red, Red Orange, Rhubarb, Sedona Sunset, Sunrise Shino, Sunset Pink, Sunshine Yellow, and Texas Rose contain Cadmium in the form of inclusion stains; in our tests, all of these glazes met FDA guidelines for cadmium release leaching tests. Blue Matt, Bronze Temmoku, Crystal Aurora, Crystal Celadon, Crystal Nebula, Crystal Lagoon, Green Matt, Green Shino, Iron Matt, Ivory Crystal, Peacock Green, Rose Crystal and Turquoise Matt are not recommended for use in food, as they may change color or texture with repeated exposure to food and dishwasher detergents. Crawl glazes (craquelle glazes) are not recommended for use in food because of their texture.

California Prop 65 Warning

California law now requires certain warnings to be prominently displayed on the website and label of any product containing material from the list of controlled chemicals. To comply, all Coyote Glazes and Underglazes now have a variation of the following warning: WARNING: This product may expose you to chemicals, including quartz and lithium carbonate, known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, visit www.P65Warnings.ca.gov

Clay and Glaze Match

Not all glazes fit well on all clays (nor do all clays fit well with all glazes), so it is always a good idea to test a glaze on the clay you are using to ensure compatibility. Each clay and glaze has its own rate of expansion (and contraction), and if they are too different, problems can arise. At about 537 degrees Celsius, the glaze solidifies and the clay and glaze undergo contraction side by side. The most common fit problem is crazing, caused by the glaze shrinking more than the clay body as it cools. This means that the glaze is stretched over the clay, resulting in a crazing or crackling pattern. While there is some evidence that crazed glaze can result in a weaker finished pot, the main concern is aesthetic, and many people just ignore it. Much more of a concern is the opposite problem of creasing. In this case, the glaze shrinks less as it cools than the clay body, putting pressure on the glaze. Some compression can be a good thing, resulting in a stronger pot, but too much can cause the glaze to flake off the pot. In extreme cases, this condition can cause the pot to break (shatter). It is important to realize that this may not come out of the kiln until days or even weeks after the work is done, so do your testing early. Expansion/contraction is often confused with baking shrinkage, which is irreversible. Expansion is temperature dependent and happens with each heating and cooling. Shrinkage says nothing about the rate of expansion. Some high shrinkage clays have low expansion rates and vice versa. Most Coyote glazes have a fairly average expansion rate and will probably fit most average clays. We have one series (the Archie’s series) that can” shiver” when used on a clay body with a high expansion rate, so make sure these glazes match the clay you are using. They include: Archie’s Base, Blue Purple, Eggplant, Gun Metal Green, Ice Blue, Opal, Red Gold and Rhubarb.