Firing Prep

Well, spent the last week glazing and finally loaded the kiln yesterday. I’d bisqued two pretty full loads, so I now have enough for about 3 glaze firings. I glazed it all hoping to do 2 or 3 firings back to back. Now that I spent 4 full days doing nothing but glazing, I’m not sure if it was a wise thing or not to try this…

Anyway, since Karatsu ware is as a rule one quarter to one third naked, and since I fire in a gas kiln for the time being, I try to think of ways to make the naked clay feet and bottoms more interesting.

One way is to fire on shells, that way you get the flashing from the salt in the shells. There is also the added benefit of keeping the pot elevated so that if the glaze runs too much, you don’t end up with footrings cemented to the senbei (the flat fireclay pads) that need to be ground off. With the shells, often just a little grinding gets everything clean. One caveat: Get the remains of the shells off of the feet before they (the shells) absorb too much moisture because they will swell, and for some reason will often remove chunks of the clay body when they do this. When you take them from the kiln the shells are still hard, but if you wait a day or so in a humid climate, you can take the stuff stuck to the pot off with a pointy steel object (pry away from your fingers and palm). Don’t forget to pack the shells with fireclay so that they don’t collapse in firing, sending your pot tumbling into the 3 others next to it, making them best friends forever. This method also has the added benefit of allowing you to level the pot easily.

The other way to get nice bottoms is rice straw. I like this one more, but if you have runny glaze you run the risk of grinding hell. Sometimes its worth risk, the random red flashed stripes on the bottom of the pots are gorgeous.

One less interesting but much easier and quicker way to set pots and prevent plucking is to put them on a little bed of rice husks, but then you get just the inside of the foot with red flashing which looks a bit unnatural. To just prevent plucking, the quick way is to keep some liquid clothing starch on hand. Quick dip the foot in the starch then quick dip in a bed of husks. Just the wet part will pick up the husks (and hang on to them), and you can set the pot right on the shelf or senbei. You can do the same thing with just water, but by the time you get the pot to the shelf most of the husks have fallen off into your other pots and have to picked out, or you end up with little razor sharp spikes in your pot. I once tried to blow them lightly out, forgetting that breath is not all that focused and all those random air currents pick up every other husk within a 30 foot radius and makes them fly into all your already set pots regardless of whether or not they are already covered by shelves or not. Only did that once…

Here I’ve done it with some small flat footless dishes. For small slabs, the husks allow the slab to expand and contract without cracking. For heavy slabs, sand works better. I put shells under each corner just in case they want to lay down.

Kiln’s firing now, hopefully I’ll have some good pictures to post day after tomorrow…

One thought on “Firing Prep”

  1. Hi mike,
    interesting photos and comments. The second layer on the raw red glaze (black after firing i suppose) is made from silicious ash, isn't it ?

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