Celina on ceramics: "Forming by pinching a bag"

Forming by pinching a bag

Pinching allows the making of any shape and one of them could be to make a bag.

After the even thickness of the pinched bowl is verified, just close the walls gradually so they end up in a joint point. Taking care that it is full of air, close it and make a vacuum, so no air should be let out.

Once the bag is closed, it is the moment of forming it by just pressing lightly around until the desired shape has been obtained.

When used to shape animals, after the body is formed, details are added as with this mouse whose tail, ears, nose, eyes and teeth were added after. The vacuum of the bag allows minute work while the clay is soft. The area where something has to be attached should be scored and slip made out from the same clay used as sticker.

“ A mouse in a flower pad” by he author

Now, if accidentally you let the air out, still it is possible to close the opening and to blow air in by piercing the wall with the help of a straw so to recover the full shape.

Finished the attachments let the bag for a while, no more than a couple of hours and then, when it is leather hard and keeps its form, make a hole in a hidden part, this will avoid the shrinking pressure of the clay to break the bag.

In the example above, the piece was firstly biscuit fired, glazed and fired to maturation. Finally, colored enamels were applied for a third, low temperature firing.

Children’s game, you say? Yes, and a bit more than that: famous American artist Michael Sherrill uses this method extruding clay pipes and closing the extremes to make a vacuum before he makes his beautiful shapes. I am not licensed to reproduce his work, but you can browse at least one of them in the following site:

http://dailyartmuse.com/2009/02/16/michael-sherrill-pottered-plants/

Also, in the “Penland Book of Ceramics” edited by Lark Books one of his works is featured in the cover.

Quite a few months ago, an artist with whom we occasionally shared a workshop, and who was working with a closed geometrical shape about 90 cm high, found that, the straight walls would become shallow when the clay shrinks in drying. I advised her to make a vacuum but the walls were too thick, and the object too big to blow air in with a straw, so I suggested her to use a bicycle pump instead, and it worked!

Celina would be pleased to try to answer any comments & questions related with her blog text, and when not able to do so, she gladly would go in quest for an answer among clay-people around.

Remember if you want to buy Celina's book about the Japanese techniques of crafting the ceramics please send an e-mail at info@forumartistico.com or visit www.e-bay.com.