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ron roy black/crystalline firing

updated thu 5 jul 07


William & Susan Schran User on tue 3 jul 07

As part of my research of crystalline glazes at ^6, I've also been testing
several "normal" ^6 glazes to use as liners inside and as a contrasting
glaze on the exterior of the pots. I needed to find glazes that could
withstand the rigors of a crystalline firing, be functional and work with
the crystalline glaze.

Several years ago I started using Ron Roy's Black that I either found
through this forum or on John Hesselberth's web site:

You can also find the recipe on my web site, below my signature, well below=

Lately I've been applying the glaze a bit thicker and voila!, the results -
an aventurine glaze! When Ron's glaze is subjected to my firing schedule:
^6, hold 10 minutes, drop down to between 1850=B0F and 2000=B0F and hold there
for 4 hours the result is a high gloss brownish black of great depth filled
with silver/gold flecks. Imagine a chunk of black glass filled with
silver/gold glitter that you look at in the sun.

Where the crystalline glaze melts down into the black glaze, there are
distinct flows of color, much like water moves down the river. The center o=
the flow is a smooth deep blue/black, surrounded by a dark blue, bordered b=
a creamy turquoise/green, bordered by a halo of golden/tan. The effect is

I have filled pots with water and allowed them to remain for several days
with no signs of leakage, so I'm fairly certain there's no crazing.

Definitely a winner!

William "Bill" Schran

Graeme Anderson on wed 4 jul 07

Hi Bill.
I've also obtained some very nice effects from a thick, stable, temoku
glaze on the exterior of a pot, and dipped the top inch or so with with a
crystal glaze containing tin oxide. Some lovely variations in colour as
the crystal glaze melted and moved down.
Cheers. Graeme.
Gemopal Pottery. Lightning Ridge. Australia.