Tonights clay tip;    "Compression"
Proper compression of your clay slabs will mean
fewer problems with your fired pieces.
Cracks and warping can be caused by improper
 handling of the clay.  When you roll your slab, by rolling pin or
machine try to roll it out in all directions, top and bottom.
Run it through the slab roller set a bit thicker than the desired
finished thickness.  Then rotate the slab 90 degrees
and run it through again at the proper thickness,
If using a pin, roll in all directions and flip it over and roll again,
this evens out the stresses in the clay made by the pressure
of the rollers.
If using the slab for a hump or slump mold, flip it onto
a piece of canvas or cotton, roll again and transfer to the mold.  Try to keep
from distorting the edges as much as possible.
If your cutting tiles keep the slab flat at all times, use the canvas
to slide the clay onto a wide enough board then move it .


A trick from Bernard Leach on tile cutting, cut partly through the clay
and leave the connected tiles on your board to dry to leather hard.
Use a knife at this stage to cut the rest of the way through.  The
tiles will lay flat because they are holding each other down and
they dry more evenly without exposed edges.
The clay connection and slower edge drying will
decrease the possibility of warping.
Works with cookie or other cut pieces also when the clay is too soft to handle.  With small pieces just leave in place and separate after they stiffen up.

Part 2
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Using clay memory to your advantage.
 
When clay is folded or bent the clay platelets on the
outside are stretched away from each other while  on the  inside they are squeezed together.

Watch the skin on your hand as you fold it in, the skin on the back of your hand will stretch but on your palm it compresses.  Our skin springs back when we open our hand but clay isn't as elastic.
Just because you unfold it and smooth it back down doesn't mean those compressed and stretched platelets have been erased.  If a careful re-compression isn't done the clay will try to return to it's bent state to some degree.
This isn't all bad though, when joining pieces of clay you can use this memory to make the parts press together.
If your adding a handle to a mug, bend it into a smaller c shape than necessary.  Open it out and attach to your piece.  As it is fired the clay will remember it's previous shape and tighten it's grip on your mug.
The edges of slab boxes will press together tightly instead of separating if gently bent toward each other and then returned to the desired flatness.
Just make these adjustments very gently.

If you have found this guide interesting or helpful please vote below, and keep watching for new ideas.

  "Have joy in everything you make"  Shoji Hamada
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