General Glaze Reference Page

Common problems and their causes/solutions:

Crazing

What is it?

The tiny cracks in a glaze surface that you can see, but cannot feel. Sometimes revealed by staining from use.

This is one of the most commonly experienced and seen issues among potters. There are a lot of explanations of the mechanics at work that cause crazing, but fundamentally it is due to the relationship between the clay body and the glaze and their specific chemistries.

It is commonly believed that crazing is due to how fast or slow your kiln cools down, but this is a myth. If a piece of work comes out not crazed but it is not a compatible clay/glaze fit, then it is only a matter of time (or thermal stress) before the crazing shows.

How to fix it:

Ultimately, this is a glaze and clay body chemical fit issue, so if the chemistry of either the glaze or the clay is known and can be altered then a testing process will likely reveal a winning combination. 

If you are looking to stop a commercially available glaze from crawling, you will have better luck finding a new clay body to fit the glaze since altering the chemical composition is not possible. This will also require testing to find compatibility, however many companies list the clay body they perform their test tiles with and this can often be a good starting point.