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glaze test results for mastering cone 6 glazes, a description.

updated wed 10 apr 02


Alisa og Claus Clausen on tue 9 apr 02

Tested on mid range stoneware with iron flecks. Fired to 1220c with the
following ramps:
100c to 600c
150c to 1100c
80c to 1220c
Hold for 15 minutes
200c (max.) down to 1020c
80c down to 800c
Kiln off
Firing time just over 14 hours.

The following is a description of the tests and results of the glazes
presented in the newly released book by John Heselberth and Ron Roy,
Mastering Cone 6 Glazes. In respect to the authors' wishes, I have not
given the recipes, but rather the page number, substitutions, if any, I
have made in the recipes, further colorant tests and a description of the
fired glaze. In general, I found the glazes best when applied thicker
than I have generally applied my glazes. All of the areas that where
double dipped produced a matter surface and/or more pronounced or lively
color. Especially true for Waterfall Brown, Variegated Slate Blue,
Variegated Blue and Spearmint
The results are as follows:


High Calcium Semimatte Base 1. page 86.

Base Glaze
Semi matte to gloss clear base. Iron oxide stripe showed well through
it. Smooth feel.

A semi gloss glaze with a brownish/yellowish ground where thickest, under a
light grey to pinkish cover of tiny, tight crystals, becoming a semi matte
where thickest.

Oatmeal with Frit 623. Same result but grayer and pinker and glossier
where thickest.

Field Mouse Brown (A favorite)
A semi gloss glaze similar in texture to Oatmeal. Ground is a slightly
purple light brown (taupe) semi gloss where thinnest and the formation of
crystals or "fur" is similar to the above, where thickest.

Field Mouse Brown with Frit 623. Similar, but more of a semi gloss overall
with a lot of fur and streaking.

Variegated Slate Blue
Semi matte to matt blue glaze with light blue matt overall and darker blue
glossier streaking. Some whitish fur
where thickest under a gloss shell. Many blue nuances throughout.

High Calcium Semimatte Base 1 with: In percent to 100 grams.

6 Rutile, 10 Ochre
Smooth semi matt with an overall beige to very pale yellow ground. White
fur throughout. Showed toasty edges where glaze is overlapped on
itself. Where thickest, the glaze is slightly more yellow.
(One of the favorite of additional color tests).

5 Tin oxide, 10 Ochre
Gloss light rust brown ground with yellowish and light greenish pooling
where thickest in ridges of test tile.

5 RIO, Frit 623
Rust brown semigloss with bright orange to red streaking throughout. Fluid
and streaking, but no dripping.

1 Cobalt Oxide, 2 Copper Carbonate
Dark Cobalt blue gloss glaze.

10 Bottle Green Stain.
Even dark green semimatte glaze.


Base Glaze
Clear semimatte glaze. Iron oxide stripe showed clearly through. Smooth feel.

With Frit 623. Same as above.

A light yellow to tan semimatte glaze with white fur throughout, especially
where thickest.

With Frit 623. Similar, but the fur is pink and red. Similar to the glaze
called Cream Breaking Red.
Streaking is amazingly pink and red in contrast to the pale ground color.

Raw Sienna
Semimatte glaze with a mustard yellowish ground. Dark rust brown
streaking and pooling in ridges of test tile.

With Frit 623. Similar but more fluid. Ground color the same, but the
streaking goes from dark rust brown to bluish and opalescent where absolute
thickest. Moving and streaky but not dripping.

Spearmint (A favorite)
Semimatte glaze with a pale green color overall. Where very thin the glaze
is glossier and a deeper, more Celadon green. Where thickest, the glaze is
semimatte and a light, lively green.

With Frit 623. Similar but more fluid. A ground of glossier dark Celadon
green, with streaking and pooling of mint green semimatte in the ridges of
the test tile.

with: in percent to 100 grams.

10 Ochre
Semimatte glaze with an overall tan to yellow ground. Some rust edges
where thinner.

1 Cobalt Oxide, 2 Chrome Carbonate
Teal blue gloss where thinnest, semimatte lighter blue with pale blue tiny,
tight crystals, where thickest.

1 Cobalt Oxide, 2 Chrome
Dark Green semigloss, even and covering. Slight teal cast, smooth.

With Frit 623
Dark teal green semi gloss, similar in color and feel to Floating Green on
John's Frogpond site.
Even and covering.


Base Glaze. Clear gloss glaze. Iron oxide stripe showed clearly through

With Frit 623. Same

Powder Blue. Subbed Black Nickel for Green Nickel.
Glossy and opaque light Blue glaze with small amount of streaking that is
slightly darker blue.
Light grayish cast. In thinner areas, glaze was browner with light blue
pools where it collected in
ridges of test tile.

With Frit 623. Same but moved more where thickest.

Clear Powder Blue.
Same as above, but glaze was not as opaque. Still covering, but color not
as even and slightly darker. More
nuances and same definition and breaking between thin and thick areas.

With Frit 623. Same but more fluid with more light blue streaking.

Variegated Blue
Semigloss glaze that is greenish where thinnest and a covering medium blue
where thickest.
The glaze also breaks green over the top of the ridges on the test tile and
pools a thick blue.

With Frit 623.
Pools opalescent fur in a dark brown gloss and breaks slightly greenish brown.

Bright Sky Blue
Semigloss glaze that is a bright sky blue with Rutile speckling or
fur. Covering.
A favorite.

With Frit 623. Dark gloss cobalt blue.

10 Ochre
Gloss dark tan glaze.


Base Glaze. Clear gloss glaze. Iron Oxide stripe showed clearly through.

Gloss covering black glaze. The blackest of any black gloss I have tried.
Brown where very thin. A breakthrough from black gloss glazes that go brown.

With Frit 623. Same.

Glossy clear glaze.


Base Glaze. Smooth white opaque semimatte glaze.

Smash It Before It Multiplies Blue.
Semigloss to gloss "white blue" glaze. This is medicine bottle blue.

Midnight Blue.
Darker version of the above and not as cold nuance. Fairly dark and covering.

It Was a Dark and Stormy Night.
Overlooked it.

Stormy Blue
Semigloss medium blue glaze with some white and Rutile speckling or
fur. Broke as a light gray gloss where

Caribbean Sea Green
A green and blue semigloss. Green where thinner and light blue where
thicker and pooled.
Smooth and covering.

Zinc Semimatte/Glossy Base Glaze with: In percent to 100 grams.
1 Cobalt Carbonate, 2 Copper Carbonate. Medium dark blue semigloss glaze
with a grayish cast.

1 Copper Carbonate. Gloss pale green glaze. Translucent.

6 Rutile, 10 Ochre.
Covering semi gloss glaze that resembles Field Mouse. Rutile dark beige
ground with greyish
fur where thickest.

9 Red Iron Oxide and 2 Copper Carbonate
Semigloss black glaze where thickest and slightly brown where thin.

10 Bottle Green Stain.
Semimatte dark green glaze, very covering.


Raspberry, page 103.

Gloss raspberry red.
I let this glaze slurry soak over 3 days.

With Frit 623. Same.

Waxwing Brown, page 105
Gloss covering glaze. Cognac sauce orange and opaque where thickest and
dark brown gloss where thinnest or breaking.

With Frit 623
Rivals Floating blue. A darker rust brown to really dark brown ground
gloss, covering. Streaks and pools cognac brown with an opalescent blue fur.

Waterfall Brown, page 107
Gloss covering glaze. Ground is dark brown with lighter brown streaking
throughout. Overall streaking and pooling with greens that are edged and
feathered with blue.

With Frit 623
50 Frit, 27 Ball, 23 Silica.
Same but more melt giving larger streaks and covering areas of the thicker
lighter brown. Same blues and greens throughout.

Ron's Cone 6 "Maiolica" Glaze, page 109

Smooth white covering semigloss glaze that lays very close to the clay.
Painted stripes of Red Iron Oxide, Cobalt Oxide and Chrome overglaze. All
well into glaze with defined edges. Chrome became a light gray and
slightly drier than other two oxides.

With Frit 623. Same, little more gloss.

Thanks John and Ron.

Best regards,
Alisa in Denmark