Monday, March 8, 2010

new glazes

We unloaded another test kiln this weekend, after which we have had to cut ourselves off. We have been obsessively testing glazes now for around three weeks now. It's actually been kind of fun. There is so much to explore and learn about glazes, and there is certainly no better way to learn than mixing up a run of glaze tests.

We often dried the tests in our oven before firing, as our little test kiln doesn't do "slow" very well. We still managed to blow up the cone pack in this picture.

So where are we now with glazes? I hate to admit to it but after the 140 or so test that we've run we're in the process of narrowing it down to three glazes (with another one or two on the way... hopefully).

We're working toward a matte white glaze for Christy to decorate over:

Christy is trying to decide between the two on the left. They both have a moderate amount of clay and feldspar, along with a substantial amount of silica. The one on the left also has quite a bit of magnesium in the forms of dolomite and talc which gives it the satin look. The one in the middle has the same amount of clay, feldspar, and silica, but only has 5% ash for the flux leaving it with a more stony look. Christy has mixed up both of these glazes for the next firing to see how they look in the wood kiln. We'll decide after that.
The glaze on the far right is also quite high in silica, and caught my eye. I've always been drawn the the traditional "nuka" glaze in Japanese pottery which is usually somewhere around equal parts feldspar, wood ash, and rice husk ash. I've seen some nice approximations of these glazes substituting silica for the rice husk ash. Unfortunately we need at least some clay in our glazes to help them adhere during the green glazing process. This glaze seems like a good start toward a nuka glaze that will work during the green glazing process. We'll probably do more testing with this one in the future.


We are also reworking our iron based glazes to incorporate our local red clay:

These are two variations on a dark iron glaze that we are working toward. Our previous dark iron glaze was fairly runny and would often turn more amber than black. We're trying to get a nice thick glaze that won't run too much. We'll give both of these a try in the upcoming wood firing. Unfortunately I lost a lot of the detail in these pictures. They both have quite a bit going on and I'm excited to see how they look in the firing.

Lastly a reworking of our iron green celedon.
The color is a little off in this picture. They are really be more olive green and less amber. These are probably the least exciting of the bunch as they look quite similar to our previous iron green glaze. All we really accomplished with this new version is working in our local red clay with which we were able to replace fireclay, bentonite, and iron. So similar outcome but a simpler reciepe and more local ingredients.... not bad.
We are still working on a matte yellow glaze for Christy, and a copper green decorating glaze to use in the third chamber (oxidation). They will both have to wait though. As I mentioned in the beginning of the post we had to cut ourselves off from more glaze testing. Our first "real" firing of the year is scheduled in less than two weeks. As in this is our last week to make pots! We really don't have that many pots made for this firing yet. None the less we are excited to see how all our new glazes look in the wood kiln!
Joe

1 comment:

ang said...

all that testing surely does pay off, can't wait to see them from your wood firing kiln, happy making pots to fill it...