The “Specifics” of Consistent Glaze Results – Workshop
This is an all levels class, suitable for anyone who controls the water content of their ceramic glazes. Measuring specific gravity and adjusting flocculation is one of the most useful practices you can adopt to improve your glaze results.
Whether you mix your own glazes or use commercial glazes, by following the simple steps that I’ll demonstrate in class, you’ll gain better control over how your glazes turn out. There is no pre-requisite to take this class, it’s available to everyone.
This is the live version of my online course that I ran in April. If you took the online course, this is an opportunity to see the steps in action and ask your specific questions.
Have you ever had a “tried and true” glaze that usually looks the same, but then sometimes it comes out looking different?
A clear glaze that goes cloudy when thick?
A glaze that runs sometimes, but not always?
A finicky glaze that never turns out the same?
The art of glazing can keep us on our toes. Nerves are high as we wait for the kiln to cool. Will our glazes look beautiful? Or will they be a disaster?
We open the kiln to discover what’s inside. Some kiln openings are cause for celebration, others make us want to give up.
Why can’t our glazes just work the way we want them to? Why does glazing have to be so complicated?
Maybe you’ve even uttered the words “I hate glazing. It’s my least favourite part of the process.”
There’s no shame in that. The struggle is real. We’ve all been there. When something feels out of our control, it can be less enjoyable.
Did you know that the physical thickness of your glaze plays a major role in the fired appearance?
A glaze might have a lot of depth and variation when thick, but appear completely flat and uniform when thin.
Some glazes turn out a completely different colour when thick vs thin.
When layering glazes, the thickness of each glaze in the combination will influence the end result.
Certain glazes work best when thick and others are best when thin.
There’s no right or wrong answer to how thick a glaze should be. This is an artistic decision you can make based on your own aesthetic preferences.
But even when you know how you like your glazes best, the tricky part is often repeating results firing after firing.
This is where my class will help you.
Do you have a way of measuring how much water you’re adding to your glazes? Or do you just add water until it seems right in the bucket? That’s what I used to do. It seemed simple enough until I started getting different results every time I glazed.
The amount of water we add to our glazes has a big impact on how our glaze will apply to our bisque. When the water content is consistent, it’s more likely that our application thickness will also be consistent.
By measuring the SPECIFIC GRAVITY of our glazes, we can see the exact ratio of solid glaze particles to water in our glaze bucket. This gives us an objective look at the water content of our glazes, no opinions required.
You can check the specific gravity at any time. You don’t need to know how much water you started with.
Specific gravity is measured by weighing a volume of glaze. I will show you all the steps to do so and the minimal equipment required.
(I will also cover the reasons why a hydrometer is not an accurate tool for specific gravity of glazes.)
When a glaze comes out of the kiln looking perfect, we can record the specific gravity number. Then it’s easy to make sure that glaze has the same amount of water every time we use it.
Specific Gravity also gives us a reference point to make adjustments if our results are too thin or too thick.
The first step to controlling glaze thickness for consistent results is to control the WATER content of our glazes by measuring SPECIFIC GRAVITY.
When we have a glaze that’s too thick, the natural response is to add water. If a glaze is too thin, we might attempt to remove some water.
But did you know that water isn’t the only factor that affects the thickness of our glazes?
There’s a concept called FLOCCULATION/DEFLOCCULATION that changes the way the clay particles in our glazes interact with each other and alters the VISCOSITY, or physical thickness of glaze.
Adding and removing water aren’t the only ways to thin or thicken a glaze.
There are scenarios where you’ll want to keep adding water, even when it’s already too thin. Then we can flocculate the glaze to thicken it back up.
There are also scenarios where adding water to a thick glaze will cause problems like cracking/crawling. Instead, we can deflocculate the glaze, to thin it down.
All without adding water!
Flocculating and deflocculating are ways of changing the viscosity of our glazes in the bucket, without adjusting the water content.
The second step to controlling glaze thickness for consistent results is to adjust the VISCOSITY by FLOCCULATING or DEFLOCCULATING as required.
Fix common glaze issues
Many glaze issues can be improved by adjusting glaze thickness. If you’ve experienced any of these glaze problems, measuring your specific gravity could help you solve them.
- Clear glaze turns out cloudy
- Glaze runs unexpectedly
- Glaze cracks before the firing
- Glaze crawls during the firing
- Glaze looks different firing to firing
- How glaze thickness affects fired results
- Factors that affect glaze application thickness (bisque temperature, application method etc)
- How certain glaze materials affect the thickness in the bucket
- How much water to add to your glazes (aka specific gravity)
- Tools and equipment for measuring specific gravity
- What is flocculation and deflocculation and why it’s important to understand
- How to repeat desired results
- Live demos of measuring specific gravity, flocculating and deflocculating