In these times, when we are so concerned about pollution and air quality. I’m amazed to find that it is still allowable to fire a fairly dirty, wood fired kiln right in the heart of Arita’s main street, old town centre.
This is a fairly old-fashioned sort of standard European, industrial, down-draught design of kiln, used early to mid last century. There is no attempt to install any scrubber or smoke minimization at all, not that I can see, and if they do have something in place it isn’t working, as is obvious from the smoke billowing from the chimney.
There are three men on shift over night, bringing it up to temperature throughout the day today. This is a stoneware reduction firing for the glaze. When this material is oxidised, it turns out a dark cream/dull beige colour. Not at all attractive. It’s because of the slight iron content. Even the hand-selected and hand-cleaned, super-white, ultra-expensive clay is just as dull. However, when this clay is reduced, it sings. It comes out a clear blue/white under a clear glaze and is a joy. This kiln is currently up to 1175oC and smack in the middle of its reduction cycle.
The air is super filthy inside the kiln shed. The ventilation is very poor, so the men have to wear paper dust masks, but they have chosen the very poorly fitting hygiene masks, that are ubiquitous here and designed to stop you breathing out or coughing on people in public and spreading mucus carried diseases. They are useless to prevent dust and smoke entering the lungs. If these guys work at this all their days, their lives will be shortened. I’m quite surprised that this is still allowed. The ventilation is so bad that it must be hell in here in summer.
I’m also surprised that they are still firing a kiln like this with wood, as all the glazed pots are stacked in saggars inside the kiln, so there will be no aesthetic of wood fly-ash contact. The saggars add extra weight to the thermal mass and makes the firing less fuel-efficient. Seeing that there is no aesthetic benefit showing on the work. I wonder why they persist, especially as everyone tells me that they are doing it so tough here now and no one is making any money. They could reduce their firing costs significantly and clean the towns’ air quality by switching to a light-weight, low-thermal-mass, gas-fired, fibre or RI brick-kiln. If there really is some sort of aesthetic reason for persisting with the wood firing, then I can’t help but feel that the kiln should be moved out-of-town, changed to a downdraught firebox, or installed with a scrubber. I’m only an ignorant outsider here and have no right to be offering anyone any opinion, but these are the thoughts that go through my mind as I watch.
There are 2 fireboxes on each side of the kiln. Most likely firing up and over a bagwall, then down through the stacks of saggars to exit flues in the floor. These fireboxes are stoked alternately, first on the left, then the one on the right, symmetrical on each side, alternating every few minutes. There is a lot of smoky flame escaping through the vent holes and spy holes in the door, walls and dome. This is to inform the fireman as to the state of the atmosphere inside the kiln. He wants to know when the smoke is lessening and about to disappear. This indicates when it is time to re-stoke the fireboxes, so as to maintain the air-starved reduction atmosphere in the chamber. If I were here, doing this, I’d have all the windows open and a vent installed in the roof to clear the smoke from the work area. Actually, I’d probably get rid of the dirty up draught fireboxes with their expensive and short-lived metal fire bars and replace them with much cleaner downdraught fireboxes. For the comfort and health of the firemen, as well as improving air quality and fuel efficiency. I wonder if they realise that all that smoke billowing out of the kiln room and chimney top, represents expensive energy wasted?
I can only suppose so. Everything has a reason here. Just because I can’t figure it out, doesn’t mean that it isn’t important and valid. It’s just not what I’m used to. Even so, I can’t help think that there will be some health ramifications for these employees, working in that filthy air.
I wonder what the towns folk think about it? Fortunately, as I’m here alone, I don’t have the language ability to get involved in this sort of in-depth conversation. Probably for the better. I don’t want to offend anyone.
Welcome to the new/old Arita!
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