Test Tiles Results

So here are the results of our test tiles. The tiles I created have three dips, so you can see at the top if crawling occurs due to being too thick.  You can see with the number carved into the tile, how the glaze responds to texture, and finally you have an Iron Oxide line on the left side of the tile, so you can see how this effects the glaze.

The pictures are with these test tiles, fired in ^6 Soda Reduction.  Next to them is a "tile" in oxidation.  I did not do these, they are the simple version of just glazing them.  there are  two exceptions that I will discuss below. This is from the last soda firing, and so it was a "dry" firing, tending towards blushing rather than orange peel

Ok so why the test tiles?  For non-potters and newbies...  In reduction, which was done in the soda firing, the oxygen in the kiln was reduced. The flames need to breath so oxygen is pulled from inside the pieces.  For some oxides this creates a chemical reaction which changes the color.  Copper Red glazes are created this way, changing a green copper to a strong copper red. This is one of the most extreme examples.  Similarly, this changes the look of the clay itself.

Also an issue, beyond reduction is the soda.  Any non-electric firing is going to have some level of reduction.  However the addition of soda adds a new chemical reaction. This tends to "bleach" the glazes, making a softer, fuzzier version.

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This is no glaze, to show the contrast I am showing the same clay fired to ^6, it happens to be the bottom of Angela's mug.

This is Egg Shell. You can see with it being too thick it will crawl. good to know. But better to know... it is ugly in reduction.

This is Fuzzy White, it turns beige in reduction.  Clearly the iron can be seen.

This is Rutile Green.  It is nice in oxidation, but you see how interesting and varied it becomes in reduction.

This is Water Fall Brown. Here we have a test tile issue, the current bucket is very thin so it affected our results.

This is Blue Fur, not much of a difference.

This is Slate Blue, you can see some of this bleaching effect.

This is Amber, and again good to know it comes out pretty ugly

This is Black, you can see a bit of a difference. The camera did not pick it up very well, there are some swirls in the glaze.

I tried a close up of the Black here to show that better.

This is Malcolm Davis Shino.  The test tile on the left was in oxidation, the right is a bowl I did.

Here there is no test tile.  This is a Celadon. The top is fired in oxidation, the bottom two are the same soda firing. So what is the issue?  More reduction in one area of the kiln than another. there is copper in this glaze, and it started to shade towards a red.  Not a bright red, there is not a lot of copper in this glaze.  (This Celadon is for ^6 oxidation, to create that look. Therefore it has copper and the green is not created from iron.)