Another Serendipitous Excitement: “Black Satin” Glaze

(2007 December 03)

Some time ago I developed a coffee-and-milk brown glaze with a semigloss surface, which you can see in the first two photos. (Teacup, collection of Dr. Harris Iskandar.) It is based on Redart Clay, to which I had to add quite a bit of flux to get it to melt. The glaze is fired to cone 9, in air, in an electric kiln.


(As usual, click any of the small images to get a larger version.)

I wanted a more silky/satiny surface, and was still tweaking and testing the glaze, when Something Peculiar happened during a firing. The next photo shows what the transformed glaze looks like. (Bowl, collection of Dr. Alfred and Isabel Bader.)

The overall color is a dark charcoal gray, and there is a dancing play of colors across it that is best seen in bright light. Where it thins out on edges and ridges it is dark red-brown.

It took me a while to figure out exactly what had caused the effect; I hope to get an article out of this, so I would prefer not to get into specifics just yet, but I can say that it is entirely reproducible, and that I now have a bucket of glaze that fires out this way every time. It is also reasonably stable: the glaze has probably been in the bucket for about two years.

This work was supported by
The Joss Research Institute
19 Main St.
Laurel  MD  20707-4303   USA

Contact Information:

Email:, where you can replace a with my first name (jon, only 3 letters, no “h”) and b with joss.

My phone number is +1 240 604 4495.

Last modified: Thu Oct 16 16:42:09 EDT 2014