This post is about a common problem that occurs with all types air dry clay. It answers the question Why does air dry clay crack and shows you how to fix cracked air dry clay.
Did you know it is perfectly normal for air dry clay to crack as it dries?
There are four reasons why air dry clay cracks and there is a very simple solution to fix cracked air dry clay.
First I will discuss Why air dry clay cracks then I will tell you how to fix cracked air dry clay.
Why does clay crack?
The first reason why clay cracks is because of the process of evaporation.
Water evaporates out of the clay as it dries. The clay hardens and as it hardens, the clay shrinks and it can causes clay to crack.
The second reason air dry cracks is if it is not conditioned properly. If clay is too dry, or too wet or too sticky it can cause cracking.
The third reason clay cracks is because the clay is too thin. Thinner pieces always dry faster than thicker pieces. Being too thin is a common reason why clay cracks as it dries.
My suggestion is to use armature like toothpick or wire for thin pieces.
Finally, if the clay is too thick it can cause cracking. This occurs because clay dries on the outside first and is it still wet on the inside.
My suggestion is to make your piece no thicker than a fourth of an inch thick. Use a pencil or tool to make your sculpture hallow on the inside.
How to fix cracked air dry clay:
Fixing air dry clay is an easy six part process.
1. Take a lump of clay
2. Fill in the crack. If you are using water-based earth clay, make a slip by adding a little water to your clay and then fill the crack in.
3. Smooth it out as much as possible and
4. Allow piece to air dry.
5. Sand if necessary after it dries!
6. Glaze it with water-based polyurethane
The following Youtube video is an excerpt of this article.
Part 1: Why does air dry clay crack?
Part 2: How to fixed cracked air dry clay starts at 02:16
Please like, follow, and tell me how you fix your clay!
A Joyful Clay Tutor 