March 26, 2012 § 2 Comments
My pressing concern at the moment is air bubbles in the clay. It has always been an issue on and off since I started to learn how to throw but having thought I’d remedied the matter it seems to have returned with a vengeance.
There are three possible causes, I think (although there may well be a multitude more…). The first is kneading; the second is related to coning up and down causing spirals to form; and the third is the way I insert my finger to create the initial hole before opening up the clay.
I use the ‘bull’s head’ method of kneading. I’ve tried to spiral knead but I know that when I do I am not kneading the clay properly, which does definitely result in air pockets, and plenty of them. I seem to create a hole at the apex of the spiral around which the clay is turning. The ‘bull’s head’ method seems to work fine; I knead it maybe a hundred times and afterwards it appears to be consistent, smooth and bubble-free.
I have tried different methods of creating the initial hole from one thumb, two thumbs, one finger inserted to create a ‘v’ shape, one finger with the thumb of my other hand adjacent to it… I haven’t stuck with one way because I have been unsettled by the issue with the air bubbles. But I don’t think that the way I am opening up the hole is causing the bubbles.
My suspicion is that the problem lies with the coning up and down. It feels to me when I’m throwing like this is when they happen. Something is happening inside the clay as it is going up and down that is causing the bubbles to form. Sometimes the top of the centred clay when I put my fingers into it is too soft, it gives too easily. When I push with my finger, the air bubbles appear and, I think, as I push I take the air bubbles down into the clay, resulting in them being all down the inside wall. There are sometimes air bubbles on the outside, too, which, I think, is because when I cone down sometimes an air pocket gets trapped on the outside. I’ve tried and tried to remedy the problem, trying to be extremely conscientious when coning up and down, making sure I am concentrating the clay in the centre of the wheelhead. Whatever I do I can’t seem to resolve the problem and it is incredibly frustrating. There are tutorials galore on youtube about every conceivable issue relating to throwing but nothing mentioning air bubbles, so I am wondering whether this is not generally a problem. I’d be a happy man, though, if I could find a way to bubble-free clay…