Friday, 5 February 2010

Beneath a Kiln.

Page 6
Factory Building Studies, Sites and Foundations, HMSO, 1960

To understand this, you really need to know a little about how brick kilns operate. I could bore you for hours on the subject of kilns, and at least a couple of those hours might be on the history of bricks. I realise that out there in the world there are people who don't know and don't care what a brick's made from, or how, or the differences beween clot-bricks and extruded or pressed one, kibbled vs.wire-cut...

The kiln in question would almost certainly have beem a Hoffman kiln. The Hoffman kiln operates a series of chambers, and fires constantly. As one chamber is firing,  its hot is passed through other chambers, preheating and drying the bricks, when it reaches temperature, the adjacent chamber's fires are lit, and air supplied to their fire passes through the just-fired chamber. The process was more efficient than the intermittent kilns previously used. Some Hoffmans fired for fifty years and more, continuously, hence the ground heating effect.

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  1. that's totally amazing that it affected the earth to that depth. not sure if you've heard of rookwood pottery in cincinnati but they've got a restaurant up there in the old pottery and you can have dinner inside the old round kiln. as i recall there was enough room for 4 or 5 tables.

  2. oh, i installed that comment saver thing... works like a dream and it works in gmail too.

  3. I've heard of Rookwood but know nothing about it, but I've been in some old, round salt-kilns, and I can easily see how they'd make an interesting restaurant.

    Comment saving, Lazarus Plugin: Yes, it works pretty much anywhere you type into a box. I'm wondering how I ever lived without it.

  4. Hey, Jim, I google Rookwood and found pics of inside the kiln!!!

    It's what we'd call a bottle-kiln, there are very few remaining now, in Britain, I think most of them are now protected as being of historic value.
    That place looks good, but the pics of the food... mmm, got me hungry, but it looks like it might be a tad pricy for my pocket.
    The bar area looked strangely similar to the bar area in my favourite brewery, old world, and well presented.

  5. hey soubriquet, it was pricey but i was being treated at the time. the other thing i remember was that there was a small museum of pieces from rookwood and as i walked in there was a beautiful vase in an enclosed glass case atop a pedestal. it had an unbelievable glaze, bright, clear and a golden orange and red hue if i remember correctly. i wasn't a potter at the time but still was struck by the glaze. as i got close enough to read the little card on the case, it stated that the glaze had uranium oxide in it. they also had a video of a man throwing while standing up and he had the strangest style of throwing, kinda like he was throwing from the back side of the pot while standing in front of the wheel.

  6. I was reading a book recently about the construction of a huge brick hospital in the 1870s and it said all the red bricks were done on-site back then. I guess they just selected a site that had the right kind of clay. Many thousands of bricks. I can't remember how it said they fired them and I can't find the book right now. Today, of course, they would just truck them in. Times change. Here is the building in question. I'll have to look harder and find that book. :)

  7. Jim: Uranium in glazes... makes a bright yellow. Add some cadmium and selenium and get reds, oranges... And a highly toxic glaze.
    I'd seen a glaze in a book with depleted uranium oxide listed, so in the 1980s I decided I had to try that... But none of the ceramics suppliers could supply uranium. Hmmm, I thought, That's a bit poor, so i set off on a hunt for some. This was, of course, long before google put the world at our fingertips.
    I used my contacts, the region's chief radiological protection officer. He put me in touch with all manner of interesting people, and finally I was offered some from british Nuclear Fuels Limited. Their people were bemused by my request, but interested enough to want to help. However, you can't transport radioactives in the post, on a train or bus or plane and so on. I had to go collect it myself from the other end of the country, or wait until they had a shipment to somewhere nearby.
    Then life got busy, and I had no time to think about it, and here I am, never got my uranium.


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