Delayed crazing-it’s a thing!
Our student Lois Aranow asked us if she was seeing things, because work she had that was originally not crazed, we’re now crazed, even though the firing was a long time ago.
A lot of you commented that the glazes in our last post were crazed. The main thing to note is that A) Crazing is based on the chemistry B) Crazing is always dependent on the exact clay body you are using. This is why some glazes craze on one body and not another.
These two test tile images at the right are exactly the same tile. The left tile was photographed after the glaze has been cool for about six hours. The right image is the exact same tile four days later.
As you can see, the glaze continued to craze, even though it was completely cool when we took the first picture. This is because crazing is caused by the stress of Thermal Expansion.
Every clay and glaze has its own thermal expansion. As they cool, they settle into their expansion and if the two are radically different, the glaze will crack to relative the stress.
In some cases it can take days, weeks months or even years for the stress to set abs and for the work craze.
There are a hundred myths out there, as how to fix crazing. 99% of those answers are myths and wrong. There is only one answer.
Chemistry.
This is a chemistry problem and that is the solution.
Want to learn more?
To learn more about how crazing works, check out our YouTube channel video to the right describing exactly what crazing is and why it happens. What you can and can’t do about it, and what are total myths.
Make sure to check out all of our YouTube Free Glaze Chemistry Lessons. To the right is one from The Middle Glazes about Reading Stull’s Map. You can also watch Rose makes a test batch of ceramic glaze in Batch, please. And don’t forget to subscribe to be notified as we add new content.
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