This free glaze class and registration for AGC are now over. They will both be offered again in the Spring 2024.

Next registration opens Spring 2024

This page is for info only and is subject to change prior to registration opening again.

Have you been wondering …?

❓ What are glazes made of?

❓ What do all the glaze materials do?

❓ How can I prevent my glaze from running onto my kiln shelves?

❓ How can I adjust my glaze from high temperature to a lower temperature (and vice versa)?

❓ What makes glazes durable and suitable for food surfaces?

❓ How can I prevent my glaze from crazing?

❓ How can I create my own unique glazes?

❓ How do I achieve a certain colour?

If you answered yes to any of these questions, you need to learn the Art of Glaze Chemistry!

Learn How Glazes are Formulated

The Art of Glaze Chemistry will teach you about:

🤓 The chemistry of glazes.

🤓 How and why they melt at different temperatures.

🤓 What gives them different types of surfaces like matte/glossy.

🤓 How you can adjust your glazes to solve common issues like runny or underfired glazes.

🤓 How to fix thermal expansion issues like crazing, shivering and dunting.

Understanding and using glaze chemistry to create and adjust glazes is definitely not an exact science. There are subtleties and nuances and various factors that affect how a glaze will turn out.

This is why I called this class The Art of Glaze Chemistry.

It’s as much art as it is science.

But don’t get me wrong. There’s plenty of science involved. The art is in how you use the science.

And I want to teach you all of it!

Test tiles by AGC student Jean Paull

What if you knew how to solve any glaze problem?

If you’ve been glazing pots for any length of time, then you probably already know that glazes can be finicky and unpredictable.

😖 Sometimes they run.

😖 Sometimes they craze.

😖 Sometimes they just look awful.

What do you do when you’re having glaze problems?

How much time do you spend trying to fix a glaze that’s not working for you?

Do you want a quick fix or a foundation of knowledge?

Glazes are complicated and rely on chemistry whether you understand it or not.

When you have challenges, you can rely on advice from other “glaze gurus”, or you can learn how to fix them through glaze testing.

It’s just like that old saying:

Give someone a fish and you’ll feed them for a day. Teach them to fish and you’ll feed them for a lifetime.

When you “learn how to fish” by learning glaze chemistry instead of relying on advice from others, you can create your own unique glazes and solve your own problems.

You’ll be able to look at a glaze recipe, understand what factors are likely causing your glaze problem and what you could test to start solving it.

Glaze troubleshooting will always require testing.

There’s no magic solution to any glaze issue that will negate the need for testing.

Join me in The Art of Glaze Chemistry and build your foundation of knowledge!

Test tiles by AGC student Sandra Lee

Join The Art of Glaze Chemistry

Registration will open Sept 21, 2023 and registration buttons will be added at that time.

Here’s everything included in The Art of Glaze Chemistry

  • Lifetime access to The Art of Glaze Chemistry program – 8 Video Modules that can be watched on your own schedule.
  • Glaze testing assignments that will give you a tangible understanding of how glaze chemistry works
  • Worksheets, action plans, presentation slides, video transcripts
  • 8 weekly Q&A sessions with Sue on Zoom (see schedule) and access to Zoom recordings
  • Private, students only community for asking questions 24/7
  • Resource library full of supplementary articles and videos to watch
  • Glazy Bonus – 2 months free Glazy Patron status to unlock features
  • Glaze Materials Workshop Bonus – instant access to my “What Do the Glaze Materials Do?” masterclass

2 Payment Options

1 x $597 USD

Pay in Full – $597 USD total

3 x $215 USD

Pay Monthly – $215 today

plus 2x monthly payments of $215 USD

= $645 USD total

Pay by credit card.

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Course Details


The one thing you need to know before taking this class is how to mix your own glazes from scratch. It will be assumed that all Art of Glaze Chemistry students already know how to do this and instructions won't be provided. If you'd like to learn how to mix your own glazes from scratch, consider taking my Glaze Mixing Essentials program.

Start Date:

The course officially starts on Sun, Oct 1, 2023 with the release of Module 1. Registration opens Sep 21 and you can get started with course prep as soon as you register.

Module Release:

Every Sunday you'll get access to a new Module. There are 8 Modules in total and we'll have 2 "Implementation weeks" throughout the course so you can get caught up on the lessons and glaze testing assignments if needed.

Lifetime Access:

Once modules are released, you have lifetime access so you can go back and review them as much as you like.

Weekly Zoom Q&A Sessions:

We'll have a 2-hour, live Q&A session over Zoom every Thursday at 10am Pacific / 1pm Eastern / 6pm UK time. The Zooms will be recorded and uploaded to your student dashboard.

Student Community:

There's a private, student community on Facebook for discussions and sharing glaze results. (There's a non-Facebook community option as well, but most students will be using the Facebook group.)

Glazy BONUS:

All students will be given 2 months of free "Patron status" on We'll be using the glaze calculation software on throughout this course. Patron status unlocks special features on the site like:

  • Target & Solve
  • Blends
  • Dark Mode
  • Calculated Thermal Expansion
  • Decimal Places
  • Limits

After your 2 free months are up, you can continue your Patron status by donating $2/month to Glazy developer, Derek Au.

What Do the Glaze Materials Do? Masterclass BONUS:

When you register, you'll also get access to my intro to glaze materials class so you can start learning the basics of chemistry right away!

Course Schedule

Here's the schedule for the Fall 2023 session.

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Here’s a list of the Modules that are released each week. Click on each one to read the topics covered in that Module.

Module 1: What is a Glaze?
  • Intro to the periodic table and the main 11 elements we use in glaze chemistry
  • Glass formers and fluxes and the purpose of each material in a glaze formula
  • The issue with soluble materials in glazes
  • Identifying why each material was added to a glaze recipe

Module 2: Chemistry and the UMF
  • Why we need to learn glaze chemistry
  • Atoms, molecules, and moles
  • Chemical analyses of materials
  • How to calculate the UMF of a glaze recipe

Module 3: The UMF and Durability
  • The basics of temperature
  • Comparing UMFs
  • The importance of glaze durability for functional wares
  • The difference between “Food Safety” and “Durability”
  • Flux ratio and durability
  • The role of B2O3 for durability at temps below cone 10
  • The “Bristol” reaction – Zinc + Calcium = lower melting temp

Module 4: Silica, Alumina and the Stull Chart
  • The Stull Chart – matte, glossy, underfired, crazing regions
  • SiO2:Al2O3 ratio
  • Properly formed matte glazes – “Stull” matte glazes
  • Understanding low alumina levels
  • Sue’s Stull research at cone 6, 2 different flux ratios
  • Adding Silica to a glaze
  • The 5:1 matte line
  • Stull shows you which direction to take to alter and fix glazes

Module 5: Glaze Formulation and Material Substitutions
  • Analyzing the UMF of glaze recipes – what to look for
  • Comparing to the UMF of known glazes
  • Intro to glaze improvements
  • What to pay attention to when substitution materials or formulating glazes from scratch
  • The issues with soluble materials
  • Oxide sourcing tips
  • Theoretical formulas for materials
  • Material substitution “Order of Operations”
  • Which materials to avoid if possible

Module 6: Colourants and Opacifiers
  • Where the colourants and opacifiers fall on the periodic table of elements
  • Examples of how colourants and opacifiers turn out differently depending on the base glaze they’re added to
  • How colour response is affected by different variables like RO flux choice and silica/alumina levels
  • Behind the scenes of colourant testing
  • The difference between the 3 opacifiers – titanium, zirconium and tin
  • How titanium is affected by cooling cycle
  • How to convert from Copper oxide to Copper carbonate in a glaze recipe

Module 7: Adjusting and Improving Glazes
  • Strategies for adjusting and improving your existing glaze recipes
  • How to change from matte to glossy and vice versa
  • How to change melting temp to fix runny or under-fired glazes
  • Thermal expansion and how to fix crazing, shivering and dunting
  • How to improve durability of your glazes
  • Using volumetric blending to test multiple variations between 2 recipes with different colourants and/or different base glaze chemistry

Module 8: The Glaze Journey Continues
  • Congratulations!! You made it to the end of this course, but this is not where the learning ends!
  • Full course review of the main, important topics covered in each module
  • A few bonus lessons added about:
    • “Limits” – their significance and how to see them on the Glazy Stull chart
    • Colourants as fluxes and the Extended UMF in Glazy
    • Calculated expansion numbers in Glazy
  • Words of encouragement from Sue about continuing on your Glaze Journey, learning at your own pace, embracing failures and sharing knowledge.

You Can Have an Advanced Understanding of Glazes

Don’t be scared! The topics are more advanced, but I promise to take you from wherever you’re currently at, all the way to having an advanced understanding with easy to follow lessons and explanations.

This course comes with lifetime access to the class recordings, so you can learn at a pace that you’re comfortable with and review as much as you like.

I hope you’re excited to take control and fully understand your glazes.

Who This Class is For:

This class is for potters/ceramic artists who have experience with glazing and already know how to mix their own glazes, but don’t yet have a clue about the chemistry.

You’d be perfect for this class if you’re familiar with the names of glaze materials but don’t understand their function. Perhaps you’ve heard of feldspar but not sure what it’s used for.

Maybe you’ve tested glazes with different colourants, but have never adapted the base recipe.

Maybe you’ve dabbled with some chemistry or material substitutions and you like to look at the UMF of your glazes but you’re not quite sure what it all means.

You do need to know how to mix a glaze from a recipe, but you don’t need any more knowledge than that.

If you want to learn how to mix glazes from scratch, consider taking my Glaze Mixing Essentials course first. Then you’ll be ready for The Art of Glaze Chemistry.

Watch the video below to learn about all 3 of my glaze courses and figure out which one will suit you where you’re at on the glaze journey.

Which Glaze Course Should I Take?

I teach 3 different glaze courses on 3 different glaze topics. This video will help you figure out where you are on the glaze journey and the next best step for you to take.

Originally recorded live in Jan 2023.

“Sue McLeod’s “The Art of Glaze Chemistry”, takes a complicated subject and breaks it down into simple steps. Having specific experiments for key ideas really gave me a visual understanding of how various components of a glaze work together. Make sure you have at lease 50 test tiles ready when the class starts, and 150 if your curiosity can get the better part of your glaze experiments!”

Barbara N.

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“This class is good for someone who is ready to learn the why’s of glaze instead of just copying recipes from the internet. You will learn how to analyze a glaze and change characteristics with Glazy. Not for the faint of heart, this is in-depth study of how a glaze is developed and altered.”
Kat R.

Make Your Glaze Testing Efforts Count

Once you fully understand the concepts I teach you in this class, which will require some glaze testing homework, you’ll be able to create, change and manipulate glaze recipes to get them working the way you want them to.

But it’s not going to be one and done. You have to be willing to put in the work, test and fail and learn and test again. I can teach you hours and hours of glaze calculation theory, but the knowledge really comes when you make the tests and then open the kiln and see results for yourself.

It’s like reading a book on how to ride a bike, versus getting on an actual bike.

The reason I have such a strong understanding of glazes is because I took classes to learn glaze chemistry and then I tested all the theories that I was learning to prove them to myself. It wasn’t until I did extensive testing that I finally felt like I really understood enough to teach others.

You’ll get out what you put into this class, but you don’t have to rush. You can take your time and I’ll be here to support you along the way. This 8 week class will just be the beginning.

Turn Glaze Confusion into Clarity and Understanding

It’s really life changing when something that can cause so much grief and frustration like glazes finally becomes rewarding when you understand why they behave the way they do and have the knowledge to troubleshoot and solve problems as they arise.

And the best part is when you can develop your very own glaze recipes out of thin air. This is what’s possible when you embrace and learn the art of glaze chemistry.

Understanding Cone 6 – a Preview of What You’ll Learn

If you’d like a glimpse of what you’ll learn in this course, watch my NCECA 2018 presentation – Understanding Cone 6. It may seem like gibberish right now, but by the end of the course, it will all make perfect sense. And don’t worry, this video focuses on cone 6 but the course covers all temperatures, not just cone 6.

If you have any desire to understand glazes on this level, then The Art of Glaze Chemistry is the perfect class for you!

An example of the testing you’ll be doing

When you take this class, I’ll be giving you some glaze testing experiments to help you understand how chemistry is affecting your fired glaze results. Once a few of you have shared your results with the group, I’ll make a video where I go through and analyze the chemistry of your glaze tests.

In this video, I go through the results of Barbara’s Remove a Material and Subbing Fluxes Experiments (Fall 2021 student) and look at them through the lens of the UMF.

If this all sounds confusing to you, not to worry! By the time we get to this part of the class, you’re going to understand everything I’m talking about.

Hopefully this will inspire you to want to understand how to look at glazes in this way.

Resources Included With the Program

You’ll have access to an extensive Resource Library full of supplementary info that I reference throughout the course, for further learning of many topics related to glazes.

Here’s a list of what’s included in the Resource Library.

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Love from my students

“This course provides the insight and resources to better understand glaze chemistry. I am so much more prepared to review and test new glazes. The ability to participate remotely in this course has been simply priceless. Thank you Sue!”
Claire O.

Frequently Asked Questions

How much studio work is assigned?

There will be glaze testing assignments throughout the course, in Modules 1, 2, 4 and 6. Expect to spend a few hours in the studio for each of these assignments. We’ll have an Implementation week after Module 3 and Module 6 to allow time to complete these assignments. This way you can get your tests fired and get my feedback on your results before the end of our time together.

How long will I have access to the course for?

You'll have lifetime access to the program so you can come back and review the lessons as much as you like.

What if I can't attend the Zoom Q&A sessions?
All Zoom Q&A sessions will be recorded so you can watch them anytime later. There's also an opportunity to pre-submit questions and I'll answer them, even if you can't attend the Zoom call live.


Does this course only focus on cone 6 glazes?

The concepts you'll learn in this class will be applicable to all glaze temperatures and you'll learn how to raise or decrease the melting temperature of a glaze.


What if I live in another country and use different materials?
I'll be teaching you how to look at the underlying chemistry of glazes, which is applicable to all materials around the world. All you need is the chemical analyses of your materials, which should be available from your ceramic supplier.


Why are the prices in US Dollars?
Since my students are international, USD is the most “universal” currency option.


What's your refund policy?

I'm offering a 12-day money back guarantee so you can complete the first 2 Modules and attend the first 2 Zoom Q&A sessions before deciding if you want to continue with the course. Refund requests must be received by Sat, Oct 29, 2022.

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Your Instructor – Sue McLeod

I’ve been mixing my own glazes from scratch since my 2nd year of art school in 2009. Learning to mix glazes solidified my love for ceramics. It added a whole other element to working with clay that I didn’t even know existed when I started.

Chemistry was my favourite subject back in high school and it was so fun to be reunited with this subject, both on an artistic level and in such a useful way.

For 6 years, I worked as a ceramics studio technician at a busy public studio in Victoria, BC, Canada, where it was my job to mix and maintain the glazes for the studio and fire the kilns. During my time in this position, I was able to really apply all the glaze chemistry I had learned in various courses in order to troubleshoot studio glaze issues, improve the chemistry of problematic glazes and study the thousands of fired pots coming out of the kilns over the years.

Learning about glaze chemistry is an endless, lifelong journey. There’s so much to explore and I would love to help you get started on your own glaze chemistry journey.

Not ready to dive into glaze chemistry yet? Check out my blog and articles published in Ceramics Monthly magazine for lots of free information, or you may be interested in some of the other classes and workshops I have available online.


All questions about the workshop can be sent through my website contact form. I’d love to hear from you!