Here's a gallery where you can see pieces made with this "Greku" enamel:
When I started thinking about this Greku, I wanted to obtain a "Snowflake" glaze. After some research on the Internet, diagram 46 of Daniel de Montmollin's book is an interesting lead.
When I first scan this diagram, I get this:
In the foreground, an area of the diagram seems conducive to the development of a snowflake glaze. You can follow the rest of this research here.
In the second row, we observe a fairly white glaze with significant braiding. The addition of India ink on the third sample clearly reveals this braiding, reminiscent of a Raku firing.
So I decided to direct my tests in this direction:
I retain the third sample and vary the contribution of silica (first row), then a greater thickness :
The thicker test seems more interesting. So I'm testing this formula on a larger piece:
The result is not satisfactory. Perhaps the enamel thickness is too thin.
I try again with a thicker enamel:
The results of this test are starting to go in the right direction.
However, small air bubbles appear and make the whole thing unsightly.
I then tried reducing the silica content to eliminate these imperfections:
Reducing silica seems to reduce the appearance of air bubbles.
I'm continuing in this direction with a lower silica intake:
The air bubbles seem to have disappeared. I select the sample on the right and glaze a new piece:
The result is much more convincing, but I would have preferred a whiter, less transparent glaze.
I then carry out another test (control sample above), adding: bone ash (row 1), Zinc Oxide (row 2), Zirconium Oxide (row 3) and Colemanite (row 4):
Tests with Zinc Oxide, Zirconium Oxide and Colemanite cause the braiding to disappear. However, the braiding persists with bone ash.
New test on a part with a concentration between the first and second test of row 1:
The result is a little disappointing, certainly due to the enamel thickness again being too thin.
I therefore carry out a thickness test:
The hypothesis seems to be confirmed: a greater enamel thickness (tests on the right) creates the desired effect.
I therefore carry out a new test by increasing the thickness:
I win! The result pleases me very much.
I therefore validate this glaze and name it Greku because it is indeed Stoneware with a Raku effect.