Cone 6 Glossy Clear is a studio favorite for a clear glaze and it also makes a great glossy base glaze for adding metallic oxides or stains. These tests show Glossy Clear mixed with cobalt carbonate ranging from 1 percent to 5 percent, resulting in an Ultramarine Glossy Blue Glaze. (Click here to see the original glossy clear post.)
The test tiles were fired in an electric kiln with a medium-slow speed and 15 minute soak at cone 6. The five tests all resulted in glossy blue glazes that did not craze or crack on the Laguna Frost Porcelain test tiles.
To my eye, the 3 percent cobalt carbonate is an ideal amount, resulting in a deep ultramarine blue. At 4 and 5 percent cobalt carbonate, a thick application starts to result in a deep midnight blue that is almost black, while the 1 and 2 percent mix was a bit light for the blue I was seeking. But your results and desired glaze color may vary, so it’s great to have options.
To make this glaze, simply mix the Cone 6 Glossy Clear glaze and include your desired amount of cobalt. After mixing with water, this glaze must be screened to break up and distribute the materials, particularly the wollastonite and cobalt carbonate. This test was mixed to a specific gravity of 1.50.
Following the recipe, there are a few images of the test tiles in different light conditions.
Cone 6 Glossy Clear Glaze with Cobalt
| Ingredient | Percentage | 3000g batch |
|---|---|---|
| Nepheline Syenite | 30 | 900g |
| Gerstley Borate | 24 | 720g |
| Silica | 20 | 600g |
| Kaolin (EPK) | 16.5 | 495g |
| Wollastonite | 9.5 | 285g |
| Talc | 2 | 60g |
| Add | ||
| Cobalt Carbonate | 3 | 90g |
| 105 | 3150g |
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Test Tile Images
These images show the test tiles in a few different light conditions, to more accurately represent this glaze.
The test tiles with some indirect Northern light.
Test tiles in a flat lighting condition.
#Glazes That Work
This recipe is part of our series of posts of glazes that just work. There’s a million glaze recipes out there, but we’re posting a series of our tried-and-true favorites. Click here to see the other recipes we’ve posted.
For more info:
Original Glossy Clear recipe post
Another Cone 6 Cobalt Blue glaze that might interest you
Read our guide on mixing glazes from scratch.
See our reviews of the best scales, cordless drills, or corded drills for mixing glazes.
Check out our recommended glazing accessories.
If you’d like to learn more about mid-range glazes, the best place to start is The Complete Guide to Mid-Range Glazes by John Britt. The book provides a comprehensive overview of materials, techniques and glaze recipes. Shop this book at amazon or bookshop.org
Do you have a favorite cone 6 cobalt blue glaze or mid range base glaze? Let us know in the comments.
