Debitus Copper Stain
The only place I know of that sells
Copper Stain such as this is Ateliers
Hervé Debitus.

Here's a link:
  • It's not expensive. But if you're not in France, adjust your expectations accordingly.
  • It's not Stain Jean Cousin
  • It's not copper sulphate, it's copper sulfide
  • It's not extremely poisonous. Here's an MSDS link for Copper Sulfide:
It only stains certain glasses. The only glasses I know of that accept it as a stain are:
  • The Tin Side of float glass
  • Bullseye 'Reactive' glasses.
  • Bullseye 1120 yellow.
I fire the stain as quickly as possible to 1200°F and hold for 30 minutes than shut off the
kiln. The provides the greatest intensity of effect on float glass that I've found.

The stain turns the previously clear glass to green and eventually a red or ruby,
depending on the amount of heatwork applied and the glass used.

When I use the stain on float glass, I never achieve more than a salmon pink tint. Maybe
more of a light red. I've seen examples of Ken Leap's tests, and some work by Sean Felix,
where they obtain a stronger red on float glass. The stronger red may be the result of a
more reactive brand of float glass, or a difference in their kiln atmosphere. But those are
just guesses on my part.

The copper stain is sold prepared in a dark brown earth pigment or powder. It is applied
similarly to silver stain.

As an experiment, I've covered the stain after application with a little slip of stainless steel
to try to effect a reducing environment. On float glass, this caused the center of the
sample to turn a true ruby red, much more intense than normal, while near the edges the
effect faded. I've done other experiments trying to lessen the oxidizing atmosphere, but I
haven't found anything I can control very well, to use on float. Instead, I use the Bullseye
glasses that easily effect a true ruby red from the stain.

Silver stain and this copper stain affect each other pretty dramatically when used together
or applied and fired separately on the same area of glass. Some of the effects would be
fun to experiment with, but I haven't pursued it.

Above: Silver stain (left side) and
copper stain (right side) on Bullseye
1120 Yellow glass. Stains were applied
and fired separately