burning your own bricks

[Alan D. Hyde]

Anyone here ever done it???

Alan

[Del Lansing]

Well close but no cigar. I did help smelt some iron one time in what looked like a termite mound made of clay. When done the clay "termite mound" had become brick from the heat. (that's a lot of help huh?) These same folks (SCA folks) had explained brick making to me and from what I gathered it is like stickered lumber (only you sticker the bricks) inbetween the bricks is the fuel, so you burn this whole mound and you get bricks. Hot enough long enough would seem to be the key. uhhh, too much coffee makes my fingers run on.... sorry

[Bruce Hooke]

Interesting question. I've fired lots of kilns built out of bricks, but never one designed to make bricks. I wonder what temperature you need to get to and how long you need to stay there to get reasonably durable bricks. I imagine it would be quite a challange to get the bricks hot enough for long enough to have bricks you would want to count on for building something permenant. You also need to be careful about the clay, especially if the bricks will be used outdoors. Only certain clays fired to certain temperatures can withstand freezing and thawing action...

[Paul Pless]

Alan,

What's your clay situation?

Paul

[stef]

It is possible to do buttt!!

The type of clay used will determine the temperature required to "fire" the brick, you could use 900C as a starting point and work up. The clay type will also govern the heat up and cool down schedule. This can be an issue equivalent to, what is the best wood for boat building or, the best paint, sail plan, etc, etc,

The size of the brick will determine the length of time at temperature (basic heat transfer).

The required number of bricks and your resolve will determine the size of the kiln. This will allow you to appreciate how much fuel will be required for a production cycle.

If you are still interested email me off the forum for more details.

Have fun by all means and enjoy the process.

Best regards,

Stef

[Alan D. Hyde]

I know that Williamsburg still burns bricks the old way.

IIRC, each batch has some soft bricks used for interior work, some clinkers used for firebrick or below-ground work, and then a little more than half the burn will usually be normal bricks.

They tread them out in a clay pit, and then fit the loaves into forms. I don't know what type of clay is most desireable, Paul, nor do I know what type of clay I have. But, located in Indiana, I do have PLENTY of clay...

Alan

Stef, IIRC, the old-time brickmakers would burn 20,000 or so in a batch, and use lots of firewood (which was plentiful & cheap), kind of in a stickered, aisled, and chimneyed mound along the lines described above...

Some art was needed, or the burn might be underdone and make soft bricks, or collapse mid-way thru the week.

[ 07-15-2004, 06:22 PM: Message edited by: Alan D. Hyde ]

[Nicholas Carey]

Originally posted by Bruce Hooke:
Interesting question. I've fired lots of kilns built out of bricks, but never one designed to make bricks. I wonder what temperature you need to get to and how long you need to stay there to get reasonably durable bricks. I imagine it would be quite a challange to get the bricks hot enough for long enough to have bricks you would want to count on for building something permenant. You also need to be careful about the clay, especially if the bricks will be used outdoors. Only certain clays fired to certain temperatures can withstand freezing and thawing action...Well…my grandfather was the general manager of the Redwing Pottery (Redwing, MN) and my uncle used to run Superior Pipe & Clay (Dover, OH). They've both created a lot of sewer pipe and brick—not that that gives me any real knowledge on the subject, but maybe it's in the genes :D

At any rate, from my understanding, for exterior use (if they'll be exposed to significant rain and/or frosts, you'll be wanting stoneware bricks.

That means you have to fire it to a sufficiently high heat that the individual silica particles in the clay begin to melt/soften and turn into glass, fusing the thing together into a non-porous mass. It's somewhat akin to forge welding where you take iron/steel to its plastic temperature.

For clay, that means you need a clay that will (A) take firing to cone 6 or 7 (2232°F/1222°C to 2264°F/1240°C).

If your clay won't take firing to stoneware temperatures or you lack the capability to fire to stoneware temperatures, the bricks need to be glazed if intended for exterior use. Salt-glazing is traditional (toss salt into the kiln while its running full-bore. At those temperatures, the NaCl vaporises and deposits itself on the kiln contents (including the kiln walls/furniture/etc.). If you're not salt-glazing, that'll also mean not one, but two firings, I believe.

Your clay needs to be have the right consistency, via grinding, the addition of water and/or sand or other adjuncts as well.

And firing it…well, consider the mass (not to consider the volume) of a useful quantity of bricks and how long it might take (and what size kiln you might need and the amount of fuel involved) to raise its temperature, say 1200&Deg;C. and what might happen if you fire it wrong, say, too high a heat too quickly, etc. A meltdown in the kiln is an ugly sight, especially when you're talking several tons of bricks fused into a big lump.

Hard to clean up, too.

I suggest a trip to the big brick building with all the books for more information on ceramics technology.

Brickmaking, notwithstanding its apparent crudity, requires a fair amount of knowledge and skill to do successfully.

And according to my dad, whose summer job in high schools was loading/unloading the kilns, it's backbreaking, miserably hot work (it takes quite a while for a a kiln full of bricks to come down to ambient temperature: you unload as soon as they're cool enough to handle.

The BBC offers this piece (http://www.bbc.co.uk/legacies/work/england/beds_herts_bucks/audio_1.shtml) by a brick maker on the firing of bricks on the old days:
Cos them days there was no machinery to, no electronic recorders or anything like that – you’d done everything by your eye, and by a long iron pole, which you put down to test your moisture, and er, and burnt by eye. And it was really interesting. You, personally, was responsible for those bricks in that chamber, and, you felt as though you were the elite of the brickyards. You felt, ‘I’m the one responsible’. And you used to go down, and when the drawers were taking the bricks out of the kiln, by hand, when they put them together they rung, and when the drawers used to say ‘Good lot’, you know, it made you fell proud that you’d done something. Mind you, if you’d overdone one of them and they was hammering ‘em to get them out, they let you know it, you know. But er, you lifted your pot, and you looked at the colour - the colour of the bricks of the fire. And, what you had to do, you had to stop it, at the temperature of about 1000 degrees you had to stop it. To stop the silicon that’s in the material, the silicon, from. You had to let it melt into glass, just enough to bind the brick together. But if you let it go too far, then it would start to crumble and melt, well melt actually, so you had to stop it melting.

[Bruce Hooke]

burnt by eyeThat line reminds me of a story. My teacher in grad school (I have an MFA in ceramics) was doing some work, with some other artists, at a brick works in Omaha. They had arranged to make use of one of the brick kilns to fire some big pieces. When they got there they found no way to measure the temperature in the kiln. So, they tracked down a fancy optical pyrometer. When the old guy at the brick works saw them using this device he said, "why didn't you just ask me?" He had fired so many kilns by eye that he could judge the temperature in the kiln to within something like 15 degrees! Remember, at the temps we are talking about everything is glowing. Someone with at least a moderate amount of experience should be able to estimate within 100 degrees or so, but 15 degrees takes one heck of an eye...

[Bruce Hooke]

Originally posted by Alan D. Hyde:
I don't know what type of clay is most desireable, Paul, nor do I know what type of clay I have. But, located in Indiana, I do have PLENTY of clay...To figure out if your clay is any good I would suggest two or three steps:

1. Talk to any local potters you can find. They may well know right off the top of their head whether your local clay is of any use for ceramics. Many potters like to experiment with local clays so they may well know about your local clay, or know someone who does.

2. If they are not sure, or if it seems worth proceeding, dig up a sample of clay, make a small tile, dry it out, and have them fire it in their next firing. I'd start by running it up in a bisque firing. If that goes OK then put it into a stoneware firing. Another option would be to run it up on it's own in a test kiln. This has the advantage of speed, and it isolates the sample from other work (the potter may well want to do a first trial in an test kiln just to make sure that the clay will not do something really nasty in the kiln that would damage other work). On the other hand, a test kiln would mean an electric firing whereas your real firing would almost certainly be a combustion firing. Clay behaves slightly differently in the two environments especially in terms of color and especially if the combustion firing is a "reduction firing" meaning the oxygen is cut back at the end of the firing.

3. A good sign that your local clay is worthwhile for bricks is the presence of old brickworks. Do a little historical research to find out where the local bricks came from and that will tell you where the good brick clay is.