I decided to continue the slab theme today since I have been so fired up about slab built pottery lately. The publishing of Slab Techniques has helped fuel this fire because it includes all kinds of tips for working with slabs.
In today’s post, we’ll concentrate on working with soft slabs in particular. If you’ve ever used soft slabs, you know that they are extra susceptible to finger marks, distortion and collapse. This posts contains tips to help avoid those problems and a project that takes advantage of soft slab malleability to make some really cool dishes. – Jennifer Harnetty, editor.
This article was excerpted from Slab Techniques,
which is available in the Ceramic Arts Daily Bookstore.
Order online and get free shipping!
Tips for Working with Soft Slabs
When the slab is first prepared, it is generally best to resist picking it up by its edges, as at this stage it is prone to stretching and distortion. Even when laid down again, the slab has a tendency to remember this change of shape, and will try to recreate it during the drying cycle.
When rolled out, the slab often sticks to the cloth or other surface, and may resist being picked up at all. The solution is to peel the cloth from the clay rather than try to pick the clay from the cloth. If you sandwich the clay and cloth between boards, and turn them over as one, the cloth can easily be removed from the clay without distortion of the slab. A paper sheet placed on the slab before it is turned over onto another board will assist drying and allow movement of the slab from one place to another. I use brown wrapping/parcel paper when available, as this resists tearing and comes off in one piece, even when wet.
It is best to make all the slabs for a piece at the same time so that they contain similar amounts of moisture throughout assembly. When you are in production mode, it is useful to be able to stack the slabs one on top of another until they are ready for use. Layers of paper will prevent them from sticking together.
Just one cautionary note: if left for an extended period of many days, newspaper will soften to the point of disintegration, go moldy, and need to be scraped off with a metal kidney. This is the last thing you need when you are finally trying to get going.
The Drop Technique
With simple slump or hump molds, bowls, dishes or shell-like shapes are possible. We get pleasure out of a simple drop technique. Place the soft slab over a wooden dish mold, similar to a picture frame. Place the frame and clay on a supporting board and drop it from waist height onto the floor. Its own weight and gravity will force the slab into the mold on impact (with a satisfying bang). This method allows very wet slabs to be instantly shaped into bowls or plates without the surface of the clay being touched or smudged. This is helpful when slip decoration has been applied.
Be sure to download your free copy of the Slab Roller Techniques and Tips: A Guide to Selecting a Slab Roller and Making Slab Pottery. This handy studio reference includes valuable technical references to help you use your slab roller to it’s greatest potential!