Monday, August 30, 2010

Decisions, Decisions

The insanity of the Blue Hill Fair is upon us. I have a glaze kiln firing starting at 3 am tomorrow morning (thank the powers that be for delay timers). If it comes out looking good, I will fill most if not all of the orders I have on the block and will have a good display for the Fair booth. I managed to inherit the display space that Rowantrees has held for decades, which was a major thing for me. I'll put up a picture of the display when I get it put together.

But about decisions...

You have to make quite a few of them when you start out on a new venture and I am no exception. Let me tell you about one of the decisions I have made.

I have decided to switch to a commercial clay. Rowantrees used the local marine clay throughout its history but that part of the tradition is not practical for me. The clay required a lot of refining to make it useful and that took machinery and time that I will not have. Besides, under the best set of circumstances, the clay often ended up with tiny rocks and other impurities in it that made for a high rate of loss in the firing. The remaining clay that I have been using is full of pebbles and it's unbelievable how many pieces I have lost in firing.

A commercial clay not only has none of these problems, but it is also manufactured for quality control. When you are doing all the jobs in the studio yourself, you have to decide what you can realistically expect of yourself. Mixing and refining clay takes a lot of time - time that I can be doing other things.

I have chosen a red earthenware body and am currently working with it. If throws nicely and is very tough and forgiving. It dries slowly and fires beautifully. It also has a higher temperature range than the local clay, which means I can experiment with increasing the firing temperature at some point in the future. This may increase the durability of the product (which isn't bad now).

There are some issues resulting from this. The glazes I have formulated do not fit the commercial clay. While they work just fine on the local clay, they craze on the new stuff. For those who have not seen it, crazing is a network of tiny cracks in the glaze that tend to show up over time. That's a matter of chemistry and I expect to get it taken care of without too much lf a fuss, but you can never tell. Sheila Varnum has been my mentor in the craft of pottery and says that there is always a problem to solve. If this is a series of mysteries, I'll roll up my sleeves and get on with it.

Fixing a crazing problem means reducing the thermal expansion of a glaze formula. I have a test of the white glaze reformulated with a lower calculated thermal expansion. It's not a drastic reduction, but it may be sufficient.

Why worry? Lots of pottery crazes. In fact, there are potteries that put out products that are purposely crazed as part of the overall decorating scheme. Fine. But those products are either purely decorative and not intended for food service or they have a "liner" glaze over the crazed layer for protection. The problem with leaving a glaze to craze is that bacteria can get a foothold in those tiny cracks. The result can be unpleasant and I have no intention of allowing my customers to get sick from using my product.

Even if pots don't turn into a science project, the crazing can weaken the pot and cause it to fail structurally. The strength of a pot lies not only in the clay matrix but in the fit of the glaze. Clay and glaze must match for maximum strength.

Ok, enough science. How about another decision?

I have intended to make tiles as part of my Lowell hill line of products. While Rowantrees reproductions will be the main focus, they will not be the only product line. I am hoping to get a small manual tile press constructed soon that will allow me to put out an ornament in time for the holiday season. While I don't plan to operate the pottery over the winter (the building has no heat and I can't afford to install any right now), I will make tiles during the cold season. Even when the temperature is below freezing I can still use the kiln to fire tiles that I make at home. With any luck I will have a modest line of tiles for sale in a few short months. Still, there's a lot of work to do to get that happening.

And when (not if) it happens, you will find out about it here. I will write more after the insanity of the Fair is over.

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