Studio Glazes

Our glazes are in a constant state of flux at the studio. We regularly introduce new glazes to give our students fresh colors and textures to explore. You can check out our food safety information here. You can also find information on basic glazing practices on our student info page. We're also excited to release our current glaze recipe book for the ceramics community to try out.

Indigo Fire 2024 Glaze Recipe Book

Wanamaker

Wanamaker is a matte, turquoise glaze with many faces. On any clay it will show three different colors depending on thickness. When thin it is a pale green, but as it thickens it moves to a charcoal green and then eventually pools bright turquoise when thick enough. It is a challenging glaze that doesn't play particularly well with other glazes. If you operate within the glaze's strengths though, you can achieve great results. It is an excellent choice for showing off texture and adding a bit of spontaneity to a pot. Be careful when glazing, drips will definitely show with this glaze.

Umoja

Umoja brings the funk. Just like Wanamaker, this glaze has many faces. While it appears matte on its own, beware because it will make most glazes it mixes with go glossy and run wild! This glaze has an unorthodox R20:RO ratio because of soda ash and lithium. It's not designed for stability, it's designed for effects! By itself on white clays it produces brilliant colors and effects. When mixed with a more neutral, gloss glaze, the copper, titanium and lithium really come through. You can get streaks of white, blue and bright green. Use this glaze carefully, our kiln shelves are quite familiar with it at this point.

Nova White

Nova White is a semi-gloss, bright white glaze. It has 16% Ultrox and 10 spodumene which makes it a strong whitener and opacifier. It's stable and reliable across all the clay bodies.

Mar Sara

Mar Sara a kaki-red glaze adapted from a John Britt straw ash recipe. It has a semi-matte finish and does spectacular things when mixed with other glazes. Despite being full of colorants, the glaze is food safe and well balanced. You can achieve bright, tomato reds on brown clay and crystalline deposits on porcelain. Pay attention to glaze thickness when using Mar Sara as it can run quite a bit when combined with other drippy glazes.

Glaze Food Safety

Each glaze at Indigo Fire is given a food safety rating of 1-5, 1 being the most food safe. The food safety rating is just a suggestion and not based on any proven toxicity with our glazes. In fact, oppositely, we've never had an instance of our glazes breaking down over time besides mild crazing in heavily use mugs which nearly always occurs. We don't send our glazes to a lab to get durability tested because we are always adjusting the recipes slightly, and a food safety rating is nullified when glazes are mixed. We don't use any lead, barium, or cadmium in our glazes. There are small amounts of materials like copper and cobalt however. So with this all in mind, our food safety rating is based on three main criteria:

1) Are there heavy metals with known toxicity in the glaze recipe

2) Is the glaze surface well melted

3) Are there significant glaze defects

So what rating is actually safe for functional tableware? Sadly there's no definitive answer. If you're selling functional pottery, there is perhaps a stronger assumption that the ware is known to be completely food safe. If you're making pots for yourself or a friend, it's a judgement call. You can use the same criteria listed above to decide for yourself. If a glaze satisfies the 2nd and 3rd criteria, you likely don't have to worry about whether or not there are heavy metals in the recipe.

It's also important to remember that the potential leaching of toxic glaze materials is something that would occur over a long period of time. Many many cycles through the dishwasher, microwave and oven are the type of thing that would degrade a weak glaze. We are exposed to trace amounts of heavy metals when working with glaze in the pottery studio and in our day to day lives. Our bodies naturally use small amounts of copper, cobalt, iron, lithium etc in normal functioning. Reducing exposure is certainly prudent though and everyone should assess their own risk. For practical purposes (given the glaze materials we work with), glaze food safety is something to be mindful of over time, but not to fear.

Glaze Food Safety

Pre-Approved Commercial Glaze Lines

Indigo Fire now allows some outside commercial glazes to be used in the studio. Our pre-approved glaze lines are below, but if you have another glaze you'd like to use that isn't on this list, you can submit it for review here using...

this Google Form

Our staff will look at the glaze and determine whether it's OK to use in the studio.

AMACO Celadon Glazes ( Cone 5 - Cone 6)

https://www.amaco.com/t/glazes-and-underglazes/high-fire/celadons

AMACO Potter's Choice Glazes (Cone 5 - Cone 6)

https://www.amaco.com/t/glazes-and-underglazes/high-fire/potters-choice

AMACO Satin Matte Glazes (Cone 5 - Cone 6)

https://www.amaco.com/t/glazes-and-underglazes/high-fire/satin-matt

MAYCO Stroke & Coat Wonderglaze (Cone 06 - Cone 10)

https://www.maycocolors.com/color/fired/stroke-coat/

As of right now, these are the only glaze lines you are allowed to purchase from. You don't need to get approval for specific colors, so long as they are from these glaze lines. Commercial glazes are functionally different than our bucket-dipping glazes. They need to be applied with a brush, usually in several coats. These glazes are NOT to be layered over or under our studio glazes. Their consistency and stability will be compromised otherwise. We cannot attest to the food safety, runny-ness, vibrancy, or finish of any of these glazes on our clay bodies. If we find that any of these glazes aren't performing well or are actively damaging our kiln shelves, we will remove them from the approved list.