How Glazes Work-shop – Level 1 – Victoria, BC

This is a Level 1 class for ceramic artists who want to better understand how glazes work from a chemistry perspective. This is the foundation class for all future chemistry classes from Sue. No previous knowledge of chemistry is required.

We will start with the very basics of what glazes are made of and end with identifying durable glazes based on their chemistry. It is helpful (but not required) to have some familiarity with the glaze mixing process and the names of common glaze materials.

(Note: This isn’t a class about how to mix or apply glazes.)

Understand the materials you’re working with:

What are those materials you’re mixing together? What does each of them do?

When you run out of a glaze material, or a recipe calls for something you don’t have, do you know what you can substitute? Are all feldspars created equal?

In this class, you will learn the basic categories of glaze materials and which category each material falls into. This will help you understand what can be substituted for what. With this knowledge, it’s possible to adjust most glaze recipes to use the materials you have on hand.

Save time:

How much time have you spent worrying about a kiln opening, not knowing if your glazes will finally turn out the way you want them to?

How much time have you spent scraping kiln shelves from runny glazes?

How much time have you spent researching online, trying to find the answers to your problems?

All that time could be spent making pots or exploring new glazes.

Learn how to fix your glazes:

Have you ever had a glaze that you loved but it ran onto your kiln shelves? Or it crazed over time? Or you wish it was glossier? More matte? Satin? Your clear glaze isn’t that clear?

These are all problems that can be solved by understanding the chemistry. The more you understand the function of your glaze materials, the easier (and faster) it is to fix glaze issues and alter recipes if needed.

Create unique new glazes using chemistry:

Even if your glazes aren’t giving you troubles, you might want to try something new. Choosing a new recipe can be a daunting task and it can take a lot of trial and error before you get what you want. More often than not, a new glaze will not perform exactly as expected or shown in a photograph.

How can you tell if a glaze will be suitable before you fire it?

Glaze recipes follow a formula that determines what they’re going to look like and what temperature they’re going to melt at. When you know how the formula works, you can make any kind of glaze at any temperature.

Knowing a small amount of chemistry will help you make better decisions when deciding which new glaze to choose.

Knowing a little more chemistry will give you the freedom to create your very own glaze recipes from scratch!

Glaze chemistry is a tool:

When you understand glaze chemistry, it doesn’t mean you stop testing glazes. Quite the opposite! With chemistry, your testing is more systematic and intentional, rather than throwing darts in the dark and hoping they hit the bulls eye.

When you understand glaze chemistry, it also doesn’t mean there will never be any mystery and excitement to the glazing process. Quite the opposite! It’s a great feeling when you design or alter a glaze and fire it for the first time and it turns out as planned.

When you understand glaze chemistry your tests will be more successful, your problems will take less time to solve and your exploration potential becomes limitless. Using chemistry to explore glazes makes your results repeatable.

You can still use your intuition and play around and say “What if I add a little of this and a little of that?” Every addition or subtraction of a material equates to a new chemical formula and you will be able to understand what has changed and why.

Keep testing my friend:

To reap the rewards of understanding glaze chemistry, you have to be willing to do the work. Mastery comes with practice. There are many layers of understanding and each kiln opening peels back another layer.

Test tiles are your friend. The more, the merrier! Put at least one glaze test into each glaze firing. Take advantage of the empty kiln space around your pots to try something new.

Now is a good time to get started! I’m going to give you a map and show you a path. Having a map can only help you if you start exploring and walking down the path.

I loved these workshops! Sue’s enthusiasm is infectious, her knowledge is great, and her teaching style makes ceramic chemistry seem accessible and FUN!

Linda Mercer

Workshop Participant

Class Outline:

  • What is a glaze? The basic components that make up our glazes.
  • The Periodic Table of Elements – which elements are used in ceramics and why?
  • Glass Formers, Stiffeners and Fluxes – where they come from, why we need them and how they all work together in a glaze.
  • Glaze Ingredients – categorized by the function they perform in a recipe.
  • Opacifiers and Colourants – how to go about finding new glaze colours?
  • Cone 10 vs Cone 6 vs Cone 04 – what determines the firing temp of your glazes?
  • Glaze Durability – what makes a glaze durable and why durability is important for functional ceramics.
  • Glaze Chemistry – why we need to learn it and why it’s not as complicated as we might think.
  • Unity Molecular Formula (UMF) – how to read and understand a formula
  • The Stull map – a guide to creating matte, satin and glossy glazes at any temperature.
  • Glaze Calculation Software – how to use it to analyze, adjust and create glaze recipes.
  • Material Substitutions – how to substitute one material for another, while keeping the chemistry the same.

Classroom format:

Class is presentation style. Handouts and note taking paper are provided. Presentation slides will be emailed to participants after the class for future reference.

There will be a visual display of test tiles to demonstrate class concepts. Class includes interactive activities and plenty of time for questions and discussion.

Date: Jul 6, 2019

Time: 10am-5pm (We will take a 1 hour break for lunch. Bring a bag lunch/plenty of lunch options nearby. Small fridge available.)

Location: Coast Collective Arts Centre, #103-318 Wale Rd, Victoria (Colwood), BC

I’m a beginner. Is this too advanced for me?

This class is best suited for anyone who is already, or plans to start making their own glazes from scratch. No previous knowledge of glaze chemistry is required. We start with the very basics and step by step, we go deeper and deeper until we’re in the depths of glaze calculations.

If you have recently started mixing glazes, this’ll be a great class for you. You’ll get to know the names of materials and see how recipes are created right from the get-go.

If you’re brand new to ceramics and you’ve never mixed a glaze before, the class will introduce a LOT of new information that may take some time to absorb. I would recommend looking up some glaze recipes in books or online before coming to class. is a great resource with recipes and photos. Get to know the names of common glaze ingredients so they are familiar when I talk about them in class.

I’ve had several students take my class who have never mixed a glaze before but have a thirst for knowledge. They all really enjoyed the class but a few felt like their brains could only take in so much info. This is completely normal. You have to start somewhere!

The information really becomes relevant when you start making and testing glaze recipes. I’ll send you a copy of all presentation slides after class so you can go back and review at your own pace.

Supply List:

Bring a tablet or laptop if you’d like to follow along during the last portion of the class where we learn to use glaze calculation software. (Optional)

If there’s a glaze you have a question about, bring both the recipe and a sample (physical or photo). Time permitting, we’ll examine and analyze your recipe as a group. (Optional)

Keep learning:

Once you complete this Level 1 class you’ll be ready to take any of my upcoming Level 2 classes, either in person or online.

Join my Facebook community:

I have a free Facebook community that you can join right now! It’s full of people who have already taken my workshops as well as people who just love talking about glazes, like I do. Please join. I’m available to answer any questions I can, whether you have taken my class or not.

Sue gave a wonderful and well-prepared presentation! She has a very clear, friendly speaking voice and it is evident that she knows a LOT about this topic and enjoys talking about it with an interested audience. Sue’s teaching style is natural and engaging. Great job!

Kit Maloney

Workshop Participant

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