Alisa Clausen on tue 29 apr 03
Colorant Swap for High Calcium Semimatte Base 1 and 2.
In these tests, I took the colorants for Base 1 and tried them in both =
the correct base and in the other "wrong" base, to compare.
I was interested to do this because the base recipes are very similar, =
with the Base 2 giving a slightly glossier glaze. I believe the first =
cooling ramp is too slow for my frit. They were less fluid and very =
appealing with the second ramp, with just a one hour hold at 800c.
I think the colorants work well in both bases. Surfaces are slightly =
different, as are the bases. From these 2 bases and 6 glazes, one could =
make 12 glazes, all that are appealing in their individual ways.
Base 1 Variegated Blue showed similar results in Base 2
Base 2 Bone, Raw Sienna and Spearmint showed similar results in Base 1.
Base 1 Oatmeal and Fieldmouse showed differently in Base 2.
Glaze tested on white midrange stoneware fired in electric oxidation to =
1220c.
Source: Mastering Cone 6 Glazes
Credited to: Ron Roy and John Hesselberth
Firing ramp:
100c p/h to 600c (212f - 1112f)
150c p/h to 1100c (330f - 2012f)=20
100c p/h to 1220c (212f - 2228f)
5 min. soak
cool down 80c per hour to 800c
shut off kiln
Recipe:
See book pages 86 - 91.
Note: All raw materials are measured up or down to the nearest whole =
decimal. =20
Colorants or additives to a 100 gram test batch are measured in percent =
to the 100 gram test batch.
Substitutions:
Frit 623 for Frit 3195
Results:
Base 1
Variegated Slate Blue =20
same as book
Oatmeal
similar ground as book, but red and blue and streaking.
Field Mouse Brown
same as book
In Base 2 ("wrong base")
Variegated Slate Blue
more crystals, but color and variegations similar.
Oatmeal
Darker ground than book with substantial streaking in blue, read and =
some areas of lighter fuzz. =20
Field Mouse Brown
Darker brown with rivulets and streaking. Moved more, leaving some thin =
areas next to heavy streaks.
Base 2
Bone
Similar to book, but pink crystals on surface.
Raw Sienna
Similar to book with streaking of lighter yellowish cream color, showing =
some read and blue small streaking on the thicker surfaces.
Spearmint
Similar to book, slightly deeper green. Many crystals on surface.
In Base 1 ("Wrong Base)
Bone
Similar to above, fewer pink crystals overall.
Raw Sienna
Matter than above but color is the same. No streaking but many color =
nuances in surface.
Spearmint
Matter than above, similar in color, but no streaking. Some color =
nuances and fewer crystals than in correct base.
Smooth and waxy.
Regards from Alisa in Denmark
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