|Our table at the East Otago Saturday Market at Waikouaiti.|
|This is from the Bodleian Library online exhibition, "The Original Wind in the Willows"|
Clay that has been stored in a bag for a long time can be wetter in the middle and drier towards the outside and it really helps to knead the clay prior to use and even out the moisture content. Clay may also have air pockets trapped in it, and we have to get rid of those. There are different techniques for preparing clay, some more effective than others.
I suspect that many people who went to pottery classes were shown "ox head" or "ram's head" wedging. At first glance the method looks a little bit like kneading bread, but it is not the same. The words "kneading" and "wedging" are often used interchangeably by potters and this may cause confusion, especially as some are adamant that there is a difference! One tidy "house rule" is to say that a bread maker kneads to get air into the dough, a potter wedges to get the air out!
Ki Cho of Echo Ceramics gives an excellent demonstration of ram's head wedging in this youtube video.
Some professional potters prepare clay like this all their working lives, it is simple and quite effective for small amounts, but a ball of clay more than 2 or 3 kilograms (4.5 -6.5 pounds) can put a serious strain on the wrists and hands, especially if the clay is rather stiff.
"Stack and Slam" is another way to do the job. A block of clay is repeatedly cut in half, turned and slammed together. After 20 or 30 repeats it is usually well mixed. 5 - 10 kilograms (11 - 22 pounds) or more can be processed at a time by this method.
|Ceramics Arts Daily. 16 September 2013.|
And then there is spiral wedging, this is something that I think was first done by potters in Eastern countries, and later came to the West. When done correctly, this is a very efficient and beautiful way of preparing larger amounts of clay. It can be rather tricky to learn, however, and there is a definite "knack" to it. There is a very helpful demonstration of this method here on youtube by a wonderful potter called Hsin-Chuen Lin.
Hsin-Chuen Lin has other excellent videos about making pots on the wheel that are a real treasure. His web site is here http://hsinchuen.wix.com/mypots
I have always had trouble following instructions on how to tie knots, all that "left over right" and "twist and through the loop" stuff has me blowing mental fuses, so I had some difficulty getting spiral wedging to happen for me, but I persisted trying it over the years, and finally got it to work quite well about a year or so ago. Where as it was difficult to do more than about 2 or 3 kg (4.5 -6.5 pounds) at a time with "ram's head" wedging, spiral wedging allowed me to tackle more than twice that amount quite comfortably and without trapping pesky air bubbles!
I think it is true to say that spiral wedging should involve your whole upper body. Wedging should not be hurried, but there is a natural rhythm that the body can get into, a bit like the swinging of a pendulum of a grandfather clock. It is good to relax, start slowly and warm up. If this is hurried, then the technique becomes faulty and arms and shoulders get overloaded.
Unfortunately, I have learned the hard way what happens when technique in spiral wedging is forced or hurried. The 16 December last year was one of those days when I felt the pressure of deadlines and overburdened with things I had to do. I was spiral wedging some clay that was a rough mixture of some stiff recycled stuff, and some newer clay of a better consistency. I powered into the task, instead of establishing an easy rhythm, and I felt a sharp pain in my left shoulder and had to stop. By evening my shoulder was telling me I was in all sorts of trouble.
I nursed the shoulder for about 5 weeks or so before I could get my hands into much clay again. Fortunately I had quite a lot of work that needed glazing, and we also were into the season of the year where we get a lot of interruptions and it is hard to do new work anyway, so I found ways to adapt my schedule to some degree, and waited it out until the shoulder felt better.
I began to do more from mid January, and thought that I had had a lucky escape, and might have done, but.... it all went badly wrong last week, which was a busy one. I consulted a doctor who confirms that it is a rotator cuff injury and I will be having a scan on Wednesday 23rd to see what has happened.
Currently I cannot work, and many basic tasks, including driving, are problematic. I think that my recovery is likely to take rather a long time from this point, so I am in the process of contacting people who have commissioned things, especially larger things, to let them know I may not be able to make them.
Anyway, let this be a cautionary tale.