Clay

I like this time of night, after everyone has gone to sleep, I can slip out to the studio and do some late night throwing.  I’ve been working on a fairly big order of mugs, and I’m over half way there.  Some mugs are in the bisque kiln as we speak, and the rest line the shelves waiting their turn.  I have to shift gears now and throw some other things. I’ve found that the gas kiln just filled with only mugs (my kiln at least) doesn’t make for a very good glaze firing.  I have to fill the kiln with pots of a variety of sizes and shapes so the flame has different paths to go, for the kiln to fire off best and most efficiently.   Spent a good chunk of the day wedging clay, weighing out balls, and prepping my wheel for another throwing cycle.  I’m ready. In fact, I am boiling the kettle right now so I can warm up my throwing water and get going.  Its so much easier to get into a groove with no interruptions.

Clay MixerThe week before I went to Canada the last time, we mixed some new batches of native clay. As you know, we use a 1915 dough mixer to do the actual mixing, but we also use a converted concrete mixer to help make a smooth clay slurry or slip.  Clay that we have ‘slaked’ down (dry clay is added to water breaks down into a slip or liquid clay) or turned into a slurry goes into the mixer first, then dry ingredients are added.  Just as when mixing bread dough, as the clay gets mixed and becomes dryer, it starts to pull together and away from the mixer walls, then its a matter of finding the right consistency you’re looking for. I like the clay to be plastic, yet still moderately soft when it comes out of the mixer.  A rough gauge to determine this is to take a small piece of clay out of the mixer,  roll it into a little coil, then twist it. If the coil breaks easily, the clay is what is considered ‘short’, and needs to mix longer. If the coil twists easily without cracking, its just the right consistency.  If mixed correctly, again, like dough, the more the clay is mixed, the better the consistency; it gives the particles more of a chance to align and become ‘plastic’ (or ‘elastic’ in consistency, in the case of bread dough).

Looking inside mixer hopper while its running

Looking inside mixer hopper while its running

Its loud and can be treacherous work, if you’re not careful. Its dusty (silica dust) too, so its important to wear a mask with a NOISH approved air filter. If you don’t have your wits about you and mess up and reach into the mixer for some reason while its going and the mixing paddle (for lack of a better word) is rotating,  before you know it, it can grab you and pull you right in. Really.  That puppy is strong and you can lose your arm or worse (!).  Sickening thought, isn’t it?  Kind of like using a pugmill. You never stick your hand in the hopper while the auger is moving, or you can say goodbye to your hand.  So much for that peaceful zenlike impression you had of making pottery!

Its a lot of work mixing your own clay, but the process doesn’t end there. After its mixed, we haul it inside where it ages some in a barrel, then it gets run through a pug mill, then I wedge it. I’ve found that despite being very careful to screen the clay, there is still a little junk left in the clay, so after it comes out of the pugmill, I wire cut the clay, pick foreign matter such as wee rocks or other undesireable bits out, and slam wedge it on my table.  Slice, pick bits out, slam the two pieces of clay down on the table.. slice, pick bits out, slam. And so it goes until the clay looks right.  Its a bit of a process, but I’d rather pick bits out now than when I’m throwing/finishing a pot, or worse yet, find popouts on pieces coming out of the kiln.  The slam wedging also helps to work air bubbles out, and helps to make the clay easier to work (easier on my wrists) when I do my final spiral wedging.  If I were just making brick or flowerpots I might not be so particular, but when the clay is going to be used for functional ware, I find its well worth the extra steps.

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2 Responses to “Clay”

  • Linda StarrNo Gravatar Says:

    What a lot of work that is, man, I have it so easy buying my clay already mixed. I wouldn’t have the stamina to do all that any longer any way. I do mix up some native Florida clay slip I use occasionally and mix my own slip and add stains to those.

    • Anne WebbNo Gravatar Says:

      Well yes it is a lot of work and its not for everyone. There are a lot of factors to decide whether you want to mix your own clay or dig and mix it. First, you need the facilities, equipment, and space. Then you have to assess if its cost effective. If you’re making a lot of pots and go through a lot of clay, buying pre-prepared clay can be very expensive. I have a friend in Canada who buys her clay a ton at a time and at least 1/3 of her cost, above and beyond the cost of the clay itself, is just shipping. Remember when you’re shipping pre-prepared pugged clay, you’re paying for the shipping of all that water in the clay. If you choose to buy your clay from a supplier, it costs considerably less to buy it in dry form, add water, and mix it yourself. Then you have to factor in the time and energy you expend mixing it. I guess you just have to assess whether its worthwhile for you and what suits your needs best.
      So how does your native clay slip work over your commercial clay body? Its kind of cool to be able to use local materials with your pots.

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