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death valley clay used as slip

updated fri 8 jun 07

 

Ann Brink on wed 30 may 07


Hi everyone,

I just put up pictures of the pots from my recent glaze firing (^7ox) on =
my blog: . On a number of them I used =
Laguna's Death Valley clay as slip, and did some carving. The pots are =
of either B-mix or Danish White clay. After bisqueing they were dipped =
in a Creme glaze which is the base glaze for Randy's Red, with only a =
small amount of iron for the creme color (sorry, don't know the exact =
amount any more)

I had tried this technique on a few mugs in my previous firing, and =
really liked how the slip turned shades of blue under the glaze. Where =
the slip is thinner, it is a brownish/lavender. The best effect is on a =
round pot with abstract splashes.

I thought there might be a lot of people who have some Death Valley clay =
on hand and might want to try this. I'm sure a high-iron slip over =
white clay is not a new idea, but I don't remember getting the blues =
before. Next firing I will try other glazes over the Death Valley =
slip. If anyone has pictures of something similar, please let me know.

Comments welcome,
Ann Brink in Lompoc CA, hoping for sunshine today.

Nathan Miller on thu 7 jun 07


>I had tried this technique on a few mugs in my previous firing, and really
liked how the slip turned shades of blue under the glaze. Where the slip is
thinner, it is a brownish/lavender. The best effect is on a round pot with
abstract splashes.
>
>I thought there might be a lot of people who have some Death Valley clay on
hand and might want to try this. I'm sure a high-iron slip over white clay
is not a new idea, but I don't remember getting the blues before. Next
firing I will try other glazes over the Death Valley slip. If anyone has
pictures of something similar, please let me know.

I've used both Oregon Coast Ranges shale and ferruginous bauxitic laterite
as slips. I've mostly used the laterite as trailing decorations. The shale
I've used as what I guess would be called an underglaze in that an entire
piece will be dipped in a shale slurry before bisque. I've found that I
need to apply it to the ware while green because if I try to do so after
bisque, the shale dries too quickly and flakes off the pot. It would also
wash off into whatever glaze I put over it.

Both materials, when a clear or blue celadon (both glazes in question are
the same base: Leach 4-3-2-1), either turn nearly black with some iron
opalescence, or exhibit oil spotting if the glaze is applied more thickly.
The results also vary depending on how thick the slip is, how heavily the
glaze is applied and whether I fire in oxidation or reduction and to what
cone (usually 10, but sometimes closer to 9 and occasionally 8.5-ish).
Here's one example:

http://i96.photobucket.com/albums/l166/Thistillium/Thistillium%20Pottery/Shalemug.jpg

-Nathan Miller
Thistillium Pottery
Newberg, OR