#Mug #60 - Drying Time

Nov 20

Written By Lony Maya Neubauer

#100Mugs100Ways

Day 60

Here is #Mug #60 - Drying Time

I need to consider many factors when drying my work before sending it be fired.

A. How Do I know when my mugs are dry enough?

When my work dries, I notice that the color of the clay turns lighter. There is a certain percentage of water in the clay of my mugs. An excellent way to tell is that the piece feels much lighter when it has completely dry.

A nice way to check if it is dry enough is to hold it against my cheek; if the clay feels like it is at room temperature or slightly cool when it touches my cheek, it is dry. However, if it feels chilly, I will give it more time.

B. I must consider the climate.

The climate is a huge factor; if it is too humid, my mugs will still be moist after a week. I need to give my work at least 1-2 weeks to dry entirely in a humid climate.

However, if the climate is dry, like the desert, a piece should be bone dry in one week or even sooner.

One bad aspect of a dryer climate is that there is a high possibility for the piece to crack, so I need to take extra precautions. I usually cover my mugs up with plastic layers and take layers off to do a slow drying process when the climate is dry.

C. The size and thickness matters

Usually, my mugs do not have thick walls, but if I were to create a piece, like a sculpture that is thicker, I would need to give it much more time to dry; again, it all depends on the climate, and for a thicker piece, it can take weeks to get it completely dry.

D. Different clay body

If I work with different clay bodies, I need to consider that the difference in the clays plays a big part in how long my work needs to dry before firing. A clay body like porcelain with high plastics and finer particles has higher water content. Consequently, my work will take longer to dry, and the shrinkage will be more significant.

The more a piece shrinks, the higher is the chance my work can crack.

If I work with clay that has grog in it, it will help reduce cracking and shrinkage, and it will dry much faster.

Grog is clay that has been fired then ground up. Grog comes in many-particle sizes, from fine to coarse. It is used to reduce shrinkage in clay bodies.

E. Uneven Drying

Clay can shrink anywhere from 2% to 14% during the drying process, which doesn’t include when the piece is fired. My work will shrink even more in the kiln.

The clays with the highest shrinkage volume can crack if not dried evenly because the drying clay is pulling away from the moist clay, and that is when separation can happen.

I also need to consider that stoneware has a higher shrinkage rate than earthware.