The number one ‘problem’ question I am asked is

 “Why did this crack?”

The number one answer 90% of the time is 


Its just that simple.


In the pottery world the normal turn around time is around 7-14 days. 

Make a pot, let it harden, trim it, bisque, glaze, high fire … Bingo! Done. 

This works very well for an object made with one non porcelain clay body, created at the same moment, shrinking at the same rate and generally playing nice.

BUT Colored Porcelain canes and patterns are a whole different world.

Your patterns and designs have thousands of places where the clay is   meeting slip on a variety of angles. You have rolled the clay, colored it, shaped it, stretched it, joined it … what haven’t you done to it on its journey to being a vessel??

You have to give the clay a chance to rest, even out and recover before you move on to the next step throughout the whole process. 

When you turn it into a cane or an image … let it REST. Depending on the complexity and size it can require anything between overnight to a week for very large work. While it is resting the humidity is evening out, the slip is attaching to the clay, the whole design is coming together rather than staying in separate parts.

When you make a vessel with the canes, again SLOW DOWN. You need to give the work time to shrink back from a rolling process. You need to cover the work any time you leave it to make sure it stays evenly humid. You have to respect all the work YOU have put into it to get it to this point.

Once finished with the making,  you cover the rims with paper, then cover the whole piece with a double layer of dry cleaner type plastic and LEAVE IT ALONE

Give it at least a few days to rest before you start unwrapping it to check on it. Give it a week before you even think of removing that first layer of plastic. Watch carefully for the first sign of a crack … a crack means you go back to the previous step.

Some potters say this is crazy. How can you do production when everything takes so long to do?? 

Well, the simple answer is that I don’t sit around and watch the pots dry. I am busy making more. So my turn around time might be 40 - 60 days but that is not for ONE POT. It is for a series of work that is usually a large number of pieces.

If you cannot imagine working that slowly … if it goes against your very nature, then consider switching away from porcelain to a white clay body that is flexible and more forgiving. Something groggy that can stand abuse and rushing. There are lots of them out there and if you use them you can work a lot faster and your colors will be just as vivid. You will sacrifice the translucent qualities of porcelain but the trade off might not matter to you.

SO, what is the answer for the other 10% of the cracks?

A sharp edged crack often means the kiln cooled too quickly. 

Firing down your kiln will eliminate a large number of cracks that are caused by the rapid cooling of electric kilns. If you have a computer controlled kiln this is an easy fix … your owners manual likely has a controlled cooling program you can run.

Sometimes it is the shape of the vessel putting pressure on one point.

Sometimes, it is just a mystery.

Copyright © Chris Campbell Pottery, LLC