WHETHER YOU GRADUATED from a well-stocked university or moved to a new town with a community studio, we’ve all been there: that moment when you may recognize a glaze or two, but much is unfamiliar. Perhaps you are now using a different clay body or considering firing to a new temperature. There could be a moment of trepidation, worry that you may coat good pots in bad glaze. In this situation I encourage you to face that fear and dive right in! In the act of searching to make your own work you have to experiment, stretch, and try new things, expecting that not all of them will work out.

You’ve heard the saying about how making an omelet requires you to break eggs? Put another way: Allow yourself to make bad art. This mentality ensures a certain emotional freedom that allows creativity to flow unimpeded, which in the end is crucial to making good art.

No matter where you are in your own journey— whether you’re new in town or feel like you’re stuck in a rut at your longtime studio—welcome! I hope you find what you are looking for in this book and that you leave inspired to glaze like you’ve never glazed before. First I’ll run through some necessary tools and best practices that will help to realize spectacular and repeatable results. Then we’ll explore the recipes and combinations. Even if you know all the basics, don’t skip this chapter. It will be useful as it relates to the recipes and glaze tiles shown throughout this book.


Allison Cochran


I don’t know about you, but I love my collection of potter’s tools! Accumulated in my travels over the past decades, I have several brushes that fit my hand perfectly and a slip trailer I have been using for more than seventeen years. You can develop a personal connection with your tools, and over time they mold themselves to your purpose. If you are just starting out, there are several types of tools that you will need while glazing and some others that are nice to have. In this section, I’ve grouped them by category and indicated the ones I think are most important.


For any glazing session, I recommend you have the following tools and materials.

Tongs a The red handled tongs, opposite, are best for dipping vertical pieces. Channel lock tongs are best for dipping plates, platters, and other horizontal pieces.

Buckets b It’s best if you can screen your glaze into a clean bucket. Glaze material can build up on the inside of a bucket, harden, and fall into the glaze as a chunk, which will invariably end up in the middle of your best piece. Also go ahead and fill a second bucket with water to clean up spills and rinse off tools.

Sponges c These are completely indispensable when glazing! Larger sponges, such as the automotive sponges you use to wash your car, are inexpensive and make cleanup a cinch. They can also be cut into smaller shapes for specific purposes, such as cleaning glaze off the bottom of your work.

Brushes d Even if you are not big on decoration, brushes in a couple of sizes make it easy to touch up a piece—such as when you need to fill in those pesky tong marks. (Note: If decoration floats your boat, check out the section on majolica.) Floppy or soft-bristled brushes that hold water, such as sumi or bamboo, are well suited for glaze work. Stiff-bristled brushes are hard to use and leave more noticeable brush marks.

Stirrers e Glazes settle out, so you need a way to remix them. A simple stir stick will get the job done, but some people prefer a giant whisk. For glazes that tend to hardpan in the bottom of the bucket, you may want to get a handheld power drill. A blunger or paint mixer attachment will make your life much easier with these glazes. An immersion blender can quickly mix up tests and reconstitute smaller amounts of glaze.

Notebook f These are an absolute necessity. Take detailed notes! It’s difficult to remember the specifics of all of your glazing and tests. You’ll thank yourself when the pots emerge days or even weeks later from the kiln completely transformed. I find a certain beauty in tattered, clay-and-glaze splattered studio notebooks. Although they remain my favorite way to document my testing, today’s smartphones can also store your results in the cloud and instantly recall them from just about anywhere. In either case, do be sure to mark the physical work so it will line it up easily with your notes.

a b b c c d f e e e
a c c d b b


If you want to mix your own glazes, you’ll need several specialty items.

Safety Gear a Any time you are working with dry materials you must wear a N-100 dust mask or a respirator with similar filters. Some glaze materials are soluble, meaning they can be absorbed through your skin, so you also may want to wear gloves when mixing and applying glaze. I like nitrile gloves, which come in several sizes. When mixing your glazes, make sure that you are outdoors or using a venting chamber like a spray booth.

Scales b OHAUS balance scales have been the standard for measuring glazes for many years. They are accurate and completely analog, but can be somewhat time-consuming to use. Digital scales, on the other hand, are quick and easy. You’ll pay less for units that measure to the gram or tenth of a gram than more sensitive models that measure to the hundredth of a gram. While the glaze recipes in this book are measured to the hundredth of a gram, you will not notice much change if you round to the nearest tenth, and you will save considerable money on your scale. We do recommend that you get a model that can measure at least 2,000 grams at a time.

Sieves c Glazes should be regularly screened to homogenize them and remove any unwanted material that may have ended up in the mix: 60- or 80-mesh screens usually suffice. A Talisman sieve will screen a 5-gallon (19-L) bucket of glaze in a matter of seconds, but you may also want a smaller handheld screen for sieving smaller batches of glaze for testing.

Hydrometer/Graduated Cylinder d To measure specific gravity, discussed shown here, you can use either a hydrometer, which is a sealed glass tube filled with lead, or a graduated cylinder, which can be used with the digital scale to measure specific gravity. A syringe can be helpful to quickly and accurately measure small volumes of glaze. Get one with a 50- or 100-ml capacity. Syringes can also be used to fill small containers such as glaze trailers (described shown here).


Although not part of the basic glazing tool kit, these items can come in handy in the right situations.

Pebble Bowls a These large bowls are great for glazing wider platters that won’t fit into your buckets. You can find them at restaurant supply stores. They are inexpensive, easy to clean, and nest inside of each other.

Trailers b Glaze, like slip, can be trailed in a running bead along the surface of your work to create a thin line of color. Trailers can also be used for other decorative techniques, such as polka-dotting. They come in all shapes and sizes. You can also use other items to trail; some people like surgical bulbs, others hair-dye bottles. Find a trailer that fits your hand and feels good to squeeze. You can cut the nozzle with a pair of scissors to get the diameter you want.

Funnels c Funnels can help you avoid a mess in many situations, from trying to glaze the inside of a narrow-necked bottle to refilling trailers when they run low.

Banding Wheels d Banding wheels allow you to rotate your piece without touching it, giving you easy access to all sides of the work. You can also use a banding wheel to create “bands” of color on your work, as in the majolica examples shown here).

Spray Gun / Compressor e Spraying glaze is a unique way to apply it to a piece, allowing you to feather, layer, and blend colors and textures. Wear a dust mask or respirator, and always spray in a ventilated booth or outdoors.

c e e b d a


There is no singular law on how to glaze. Among artists, glazing practices vary from impeccably precise and exacting to quite casual and relaxed. Although there is no one right way to do things, I have found that these best practices will help you gain more control over your glazing process and avoid undesired outcomes.

Mixing, Slaking, and Screening Glazes If you mix your glazes from scratch, carefully weigh out your ingredients in a well-ventilated area while wearing a dust mask or respirator. To slake, in a separate bucket, measure out 700 g water for every 1,000 g of dry materials. You can pour the dry materials into the water or the water into the dry materials. In either case, I recommend that you do this outdoors to avoid dust in the studio. Mix up the materials with a blunger or immersion blender. Sieve twice through a 60- to 80-mesh screen or until smooth. Stir up and screen your glazes into a clean bucket each glazing session. If your glaze sits for more than two or three minutes, stir it back up before glazing so it doesn’t settle out.

Measuring Specific Gravity Measuring specific gravity is an extremely important, but often overlooked, way to ensure regularity in your glazing process. Specific gravity describes a material’s density relative to water. There are two methods I recommend to measure specific gravity: Use a hydrometer or weigh 100 ml of glaze.


Screening glazes twice is important if you want a silky-smooth mixture.

  • The hydrometer is a sealed glass tube that has been calibrated to float in liquids denser than water (which receives a base measurement of 1000). To use the hydrometer, mix up and screen your glaze and then gently place the hydrometer in the glaze allowing it to sink until it stops moving. Take the reading on the outside of the hydrometer at the level of the glaze.
  • You can also use a graduated cylinder and digital scale to weigh 100 ml of glaze. Because the materials added to water to make glaze have a greater density than water, the specific gravity of glaze will always be greater than 100. Multiply by 10 to get the specific gravity of 1,000 ml of glaze, which will then express itself in the 1,000s. For example, you measured 100 ml of glaze and found that it weighs 150 g, so 150 x 10 = SG 1500.

A hydrometer is the easiest way to ensure your glazes are the proper thickness before application.

Glazes in this book should be mixed between SG 1450 and SG 1500, unless otherwise noted. Whichever method you choose, stick to it for consistency. If a glaze is too dense, you can add water, rescreen, and remeasure the specific gravity. If a glaze is not dense enough, you can leave the lid off the bucket overnight to let some of the water evaporate and remeasure the next day. If you can’t wait overnight (or the weather is particularly humid), another way to thicken the glaze is to mix up another small batch (100–1,000 g) of the recipe, dry, and add it to the glaze until you get the desired specific gravity. Mix well and rescreen before measuring, if you use this method.


When applying glaze, the object is to get just the right amount of glaze exactly where you want it. There are several factors that determine how much glaze ends up on your piece. The first is your bisque temperature: a higher cone creates denser bisque that absorbs less glaze, while firing to a lower cone results in a more porous clay that absorbs more glaze. Try to keep your bisque fire temperature consistent (cone 04 recommended) or you’ll notice a change in the way the glazes perform. Other factors that affect glaze application include the specific gravity and pH of your glaze, and your use of the Count, explained opposite.

There are many ways to apply glaze, including dipping, pouring, brushing, sponging, spraying, and trailing. Each method has its advantages. Dipping can cover large areas quickly and evenly. Brushing allows for a painterly approach, and spraying enables you to feather glazes on top of each other. Experiment with different types of glaze application to figure out which ones you like the most.

The object of each method is to apply glaze to a specific area of the pot in a desired thickness. The coat thickness of the glaze on the pot is a major factor (in conjunction with firing) in how it performs. Measuring glaze thickness can be done by eye, with a needle tool, or with a depth micrometer.


Hank Goodman and the Importance of Apprenticeship

Like many professional potters, I apprenticed with an established master for several years. While I apprenticed with him, Hank Goodman, a giant man with a giant personality, specialized in fine, ash-glazed stoneware. Having established himself as one of the premier practitioners of the craft in the United States, the demand for his work was tremendous. Hank and his two apprentices (myself alongside Adrian Sandstrom, shown here, here and here) worked his three-person stoneware factory, turning and shaping nearly 12,000 pounds (5443.1 kg) of clay a year.

At that time, Hanks’s pots began with a custom stoneware blend he had developed to showcase his ash glazes. A local supplier mixed two tons at a time, and when a delivery arrived we would stack it neatly by the pug mill. The pug mill was used to adjust the moisture level of the clay according to Hank’s daily instruction: soft as could be for his large mezzanine platters, or more firm for the vertical forms and vases (see images). While we worked, we would watch Hank throw out of the corner of our eyes, taking in the dance of man and material choreographed to a nonstop soundtrack of Jazz and the Blues: Miles Davis, Howlin’ Wolf, Muddy Watters, and Bessie Smith. A hundred freshly thrown mugs would appear in a morning to be handled the next day. The carts would quickly fill with batches of casseroles and pitchers. And everything moved to the beat of a driving bass drum and steel guitar.

We worked incredibly hard to keep up with his orders, loading and firing his self-designed, 100-cubic-foot (2.83 m3), all-fiber, flat-top kiln on a weekly basis. This experience gave me an education in sieving seemingly endless amounts of ash, mixing and spraying glazes, and firing a gas kiln in reduction. Although Hank did all of the throwing, we were allowed to trim some of the pots, did much of the glazing, and produced a separate and highly successful line of ash-glazed, slab-built dinnerware. Although he was always experimenting, introducing two new glazes he developed during my time with him, he also had an established group of glazes that he had worked with for more than a decade. He knew these like the back of his hand. We mixed these glazes in gigantic batches of 50,000 to 100,000 grams, which fit neatly into 55-gallon (208-L) drums, thus making glazing larger work a cinch.


Basket Vase. Sprayed glazes highlight stamped textures in this tall-handled basket.


Slip Trailed Casserole. This is a beautiful example of glaze rivulets, a highly desired characteristic in ash glazes. Cobalt carbonate colors the glaze deep midnight blue.


Mezzanine Platter. Copper red peeks through the pierced mezzanine decorated in sprayed matte glazes.


TGR Vase. Copper ash glaze playfully interacts with slip trail lines on this double tall vase.

In exchange for our work, Hank provided us with our own studios, free clay, and firing space in the kiln. We also got the chance to experiment in Hank’s well-stocked glaze kitchen. It was a formative time in my development as a potter. Hank shared his techniques and insights, his knowledge of the business, and his unique philosophy of clay. Although he pulled no punches in critiques, his apprentices have inherited his seriousness about the craft and are driven to achieve great things within the field. Hank is a man to whom I am truly grateful, a great American potter.


The savvy clay artist knows to look before leaping, to test a new recipe or combination before glazing an entire kiln load. If the results are less than desirable, the ability to alter your glaze to get the effect you want can prove invaluable. Here are some guidelines for testing and altering glazes.


A variety of types of test tiles: check out Kathleen Lizzul’s “mini-goddesses.”


Once you’ve properly prepped your glaze, always test it first before glazing a whole kiln load. Have test tiles on the ready, and make an attempt to try something new every time you fire. The test tiles themselves should be little works of art that represent your style so they give you meaningful information about how the glazes will perform on your work. The test tiles for this book are wheel-thrown tumblers, quick to make and tall enough to show how far a combination will run, but also a saleable item when they turn out well.

When testing a new glaze, apply one coat and let it dry. You may want to apply a second or even third coat near the top of the tile to get more information about how the glaze performs when applied more thickly. Similarly, test new combinations on a tile: Dip the entire piece in the first glaze. Let it dry. Then apply subsequent layers of glaze toward the top of the piece until you can see how they interact.

Progression Tests A progression test is one in which you add (or subtract) material in regular intervals to alter the way a glaze performs. Change only one material at a time in these tests so you can isolate its effect. Progression tests can be used to alter the texture or color of glazes. They can also be used to treat glaze defects. For example, if a glaze is crazing, experiment by adding silica in 3 percent intervals until you reach a desirable level of thermal expansion that doesn’t craze over your clay body.

You can also perform progression tests with coloring oxides and mason stains (see here) to develop the colors in your glazes. Most coloring oxides can be increased 1 to 2 percent at a time. Cobalt carbonate and chrome oxide are particularly strong and should be increased in 0.5 percent intervals or less. I generally test mason stains at 3, 6, 9, and 12 percent to start. You can run a further set of progression tests based on the initial results.


Blends combine two or more ingredients to show their interactions at different proportions. Blends are extremely useful tests with many applications for the clay artist. For example, blends can be performed with individual ingredients or entire recipes. You can blend clays, glazes, even underglazes (see Allison Cochran’s profile). The following are several types of blends you can try:


The simplest type of blend, a line blend, involves two ingredients blended at regular intervals. The length and frequency of the interval is up to you. The simplest line blend takes as little as three measurements. These can be done by volume or by weight.

Ingredient A: 100%

Ingredient A: 50% — Ingredient B: 50%

Ingredient B: 100%

More commonly, you will find an 11-point blend that looks as follows:

11-Point Line Blend

A: 100%

B: 0%

A: 90%  

B: 10%

A: 80%  

B: 20%

A: 70%  

B: 30%

A: 60%  

B: 40%

A: 50%  

B: 50%

A: 40%  

B: 60%

A: 30%  

B: 70%

A: 20%  

B: 80%

A: 10%  

B: 90%

A: 0%    

B: 100%

Use a line blend to see how two glazes look blended at different intervals. Try using dry materials by weight or wet glaze by volume. For wet glaze, note the specific gravity of each glaze so you can replicate the results. For dry glaze, add the same amount of water to each cup. Start with 70 g water for every 100 g dry materials. Also try a line blend to test combinations of coloring oxides or mason stains to be added to a base glaze.


Triaxial blends involve three ingredient groups usually arranged in a triangular grid with 15, 21, or 66 points, (see below). Similar to line blends, triaxial blends can have many applications. They can be used to create simple base glazes from three ingredients or investigate the possibilities using three colorants in a base glaze. A triaxial blend chart might look like this:

21-point Triaxial Blend

A:100% B:0% C:0%

A:80% B:20% C 0%

A:80% B:0% C:20%

A:60% B:40% C 0%

A:60% B:20% C:20%

A:60% B:0% C:40%

A:40% B:60% C:0%

A:40% B:40% C:20%

A:40% B:20% C:40%

A:40% B:0% C:60%

A:20% B:80% C:0%

A:20% B:60 % C:20%

A:20% B:40% C:40%

A:20% B:20% C:60%

A:20% B:0% C:80%

A:0% B:100% C:0%

A:0% B:80% C:20%

A:0% B:60% C:40%

A:0% B:40% C:60%

A:0% B:20% C:80%

A:0% B:0% C:100%

Note that in this example, the three lines (A, B, C) that connect the triangle are themselves line blends.


I took a ceramic material science class from the great Frank Bosco at Rhode Island School of Design in 1997. It was the first time I had been exposed to this material and felt overwhelmed by the sheer volume and technical nature of the course. There were so many chemicals involved! You had to know their molecular weights! What the heck is the Unity formula, anyway?!

Frank patiently taught us, familiarizing us with the common ingredients and their properties, and showing us how they relate on a chemical level. He covered testing and blends, and he casually mentioned that few people would get as far as trying a quadraxial blend. Though I felt a bit over my head, I tried a 35-point Currie blend, a type of quadraxial blend, chasing a satiny mint green glaze at cone 6. Though not all the combinations were beautiful, there were more than a couple of lively possibilities within the grid. It opened my eyes to the scientific nature of inquiry that could inform the ceramic process—and to the fact that small variations in recipes could noticeably improve them. A simple 25-point quadraxial blend looks like this:

25-Point Quadraxial Blend

A:100% B:0%

A:75% B:25%

A:50% B:50%

A:25% B:75%

A:0% B:100%

C:0% D:O%

C:0% D:O%

C:0% D:O%

C:0% D:O%

C:0% D:0%

A:75% B:0%

A:56% B:19%

A:37.5% B:37.5%

A:19% B:56%

A:0% B:75%

C:25% D:O%

C:19% D:6%

C:12.5% D:12.5%

C:6% D:19%

C:0% D:25%

A:50% B:0%

A:37.5% B:12.5%

A:25% B:25%

A:12.5% B:37.5%

A:0% B:50%

C:50% D:O%

C:37.5% D:12.5%

C:25% D:25%

C:12.5% D:37.5%

C:0% D:50%

A:25% B:0%

A:19% B:6%

A:12.5% B:12.5%

A:6% B:19%

A:0% B:25%

C:75% D:O%

C:56% D:19%

C:37.5% D:37.5%

C:19% D:56%

C:0% D:75%

A:0% B:0%

A:0% B:0%

A:0% B:0%

A:0% B:0%

A:0% B:0%

C:100% D:O%

C:75% D:25%

C:50% D:5O%

C:25% D:75%

C:0% D:10O%

The importance of testing cannot be understated. Simply put, your work cannot advance without it. So create a ritual out of testing. Dedicate a little time each month to making test tiles and doing research. Try to put at least one test in every kiln you fire. Soon you will fill your notebook, expand your palette, and have your studio mates asking how you got that amazing result!


Allison Cochran and the Art of the Test

To become a resident artist at Odyssey Clay- Works, you must meet some unique criteria. A passion for the materials and the ability to create excitement about your process are absolutely required. You must also be bright-eyed, loving, and community minded. I look not just for competence in terms of technique, but depth of character both inside the studio and out. It is my opinion that a true artist does not stop being creative when she leaves the studio.

Colorist par excellence, from-scratch baker, and high school cheerleading coach, Allison Cochran is the complete package. Allison first impressed me with her study of axial systems and the production-style slip-casting methods she uses to create vibrant, colored clay installations. An “axial system” combines multiple blends that share one or more common ingredient. Allison has created systems with as many as 240 individual blends on a mission to “create a large vocabulary of color in ceramics.”

In the tradition of Jane Pieser and Curtis Benzle, her work seeks to push the field of ceramics forward, and has revealed several never-seen-before combinations of mason stained slips. Allison is a kind of ceramic astronomer who researches new galaxies while making connections about how the clay universe functions. She also makes her kids classes super fun, can do a triple back handspring, and brings chocolate chip cookies to staff meetings. She was an easy choice.

Allison’s process begins with paper templates used to create a solid clay prototype. She pours a small shell of plaster on the model and then digs the clay out. Plaster is poured into the shell and, once set, the shell is chipped off. This plaster prototype is sanded and refined and then used to make a mold for slip casting. The mold produces a hollow version of the original prototype. Allison then integrates her axial systems. Using line, triaxial, quadriaxial, and even pentaxial blends (see image) of mason stains, Allison mixes up hundreds of different colored slips that are then cast into identical shapes in the mold. Once fired, they are arranged to visually represent the test in geometric patterns. The effect is mathematically perfect and relaxing to the eye.

The colored slips she has developed are then used to create larger works consisting of streamlined forms that are grouped together in series. The lovely pastel colors Allison has achieved illustrate the benefit of running tests and show the art of the process. This is a powerful young artist. I am proud to be her cheerleader. Just don’t ask me to do the back handspring.


Allison Cochran’s tiles on the installation wall in the gallery at Odyssey ClayWorks.


This color study in clay lays out in a perfect mathematical rhythm.


Pitcher and Cup. Allison glazes the inside of the pitcher and cup. She leaves the outside unglazed so the user will experience the smooth, tactile quality of the unglazed colored porcelain.


Double Walled Whiskey Sippers. Slip casting supplies perfectly matching forms while the choice of colored clays provides variation on the theme.


Color studies on stackable tiles line the shelves of the artist.

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