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Showing posts from July 15, 2012

Kiln Firing 1

So, the first test batch of bricks came out of the kiln, and I immediately set about smashing them. I had tested different proportions of sand and grog and I wanted to find out what was stronger. 

I realized that grog makes stronger bricks- the ones made with sand were more crumbly and powdery. I think, though, that might be also due to the size of the particles. The sand I used was very fine, whereas the grog was coarser (see below). I also realized that the thicker bricks, like the one above, did not fire evenly all the way through. I have to design my module to be thinner.

The mold I tested with a centre block did not work very well because I made the mistake of leaving the block in the clay while it dried, so the clay cracked from the shrinkage. I fired only a piece of the resulting brick- the colour difference is visible in the photo.


Clay used for making bricks must be mixed with fine-grained inert material to prevent cracking during drying and firing. Normally, sand is used, but grog, crushed fired brick, can serve the same purpose. I crushed some of the leftover tiles that we made in April and mixed them into a test batch of clay. I don't think this is a viable option for all the bricks due to time constraints, but it is good to know that all the materials for the brick itself can come from the same site.

Tool development

I find that I am doing many tiny design projects as I go- one of them is to make my own clay sifter. The first one I made, with window screen, broke as soon as I threw the first handful of flinty clay onto it:

I then had to get a stronger screen, which came in smaller pieces, and the frame I made was just slightly shorter than the recycling bin in which I'm collecting the clay. As well, after a week of beating it was in very poor shape:

 So, I had to make another version. This time, I made the ends thicker, which will hopefully add strength as well as being a more convenient length.

Fire at the Quarry

There was a lot of sawdust from the fabrication projects that are happening here, so I thought I'd try pit firing some clay. There was a convenient hole left over from the digging, so I just filled it with sawdust and lit it.

 It didn't turn out like I was hoping- I think the volume of sawdust was so great that it smothered itself. I did manage to dry a couple of bucketfuls of clay, though, so I can crush it and mix it with the stuff that is too wet.


Brick construction is still widely used in Warsaw, but from my observations, there is only one dominant company and type of brick: the Wienerberger Porotherm. These blocks are quite large- they can be over 30cm thick- but are still light enough to be handled by one worker. This is due to their honeycomb-like structure, with many thin walls of clay. Their structure and composition also makes them good insulators, which would explain their popularity.

Wienerberger is, according to their website, the 'world's largest producer of bricks'. Production, however, is decentralized, and many countries have multiple quarries and factories all producing brick to Wienerberger specifications. There are thirteen in Poland, with the nearest to Warsaw being Zielonka, less than 20km away. The standardized properties include size, shape, and recipe- some of their clay blocks call for the addition of sawdust to the raw clay, which burns off in the kiln to produce microscopic air pockets, thus …

Module matters

Clay is such a versatile material that there is nothing that dictates an 'appropriate' form for it to take. There is no grain or vein to be respected, like that of stone or wood. It is even arguably more flexible than other homogeneous substances such as concrete and plaster because in its raw state it is not a liquid, but a plastic paste that can be worked by hand. 

As such, the criteria for the development of brick modules are not imposed by the material, but are at the discretion of the designer. In my case, I started with the idea of a 'notch'- something that might reduce the amount of material needed for each module, as well as provide a way that they could lock together. 

The Strangest Museum

On the same walk with the employee from the Historical Museum of Warsaw, he stopped in front of a nondescript apartment complex and rang the buzzer. At the front desk, he spoke with the security guard and flashed his museum badge so that we could get into the courtyard. Isolated in the middle of the courtyard was a piece of building that had been encased in a conservatory-like construction.

These are the remains of a synagogue- a rare reminder of a segment of Warsaw's population that was almost completely eradicated. But what a strange way to treat it- preserving it meticulously, but for no one to see.