Terra sigilatta made and used according
to the following method is
Versatile, Quick and Cheap! It also provides the artist with the opportunity
to
develop a personal palette--so your work doesn't look like everyone else's who
buy the same commercial underglazes.
The beauty of this system is the wide
variety of colors and surfaces
available with limited raw materials and equipment. To eliminate the need for
a
gram scale and to simplify the mixing process, all color measurements are by
volume.
Using Terra Sigilatta links us with
our oldest historical ceramic
traditions. It means "sealed earth" and was first used
before glazes were invented
as a way to seal containers containing liquids. For some beautiful historical
examples visualize the magnificent and Pre-Columbian
Pottery.
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Terra
Sigilatta Base Recipe
- Add 14 lb. XX Sagger Clay or
7 lbs clay
To 3 Gallons + 3 Quarts Hot Water or 1 Gal+3 Qts+1Pt
Water.
- Drill up well in 5 Gallon Bucket until there are no
lumps.
- Pour in slowly, while mixing, 2/3 cup ( or 1/3 ) sodium
silicate, until
consistency of mixture changes.
- Let sit for one week. (Heavy
particles will settle
to the bottom. Water will rise to the top. Siphon out fine
particles in the
middle.)
Color Palette
All measurements are per 1 cup terra sigilatta base. Mix
in a blender, or
better yet, use a hand mixer directly in the container.
- White: terra sigilatta base.
- Oxides: Green: 2 tsp. CrO2:
- Pale Orange: 1/2 tsp. Red
FeO2.
- Warm brown: 1 TBS. Red
FeO2:
- Soft Mustard Gold: 1 TBS Rutile Mason Stains
- Dark
grey/Black: 4 tsp black stain *(Z 560)
- Dark pink: 1 TBS. Deep Crimson*(#6006)
- Rich Purple: 1 TBS. Mulberry*
(#6387)
- Teal: 1/2 TBS. Blue Stain* + 1/2
TBS. CrO2
- Rich Blue: 1 tsp.Mazarine Blue*(#6300) + 1/2 TBS. Delphinium
Blue*(6308).
- US Pigment Yellow: 1 TBS. Strong Yellow*(#6440)
Brush on 2 coats on wet, leather
hard, or dry greenware. If applied too
thickly, flaking will occur. To improve fit using
refractory commercial stains,
add 1/4 tsp Frit 3124 per cup terra sigilatta. Bisque
to Cone 04. Keep
stirring while using as the colors - whose particles
are heavier that the terra sig.
- will settle to the bottom of the container.
Experiment and create your own favorite range of colors.
Surface Treatments
- Before bisque, burnish with fingers, dry cleaning plastic,
nylon stocking,
chamois cloth, spoon or polishing stone. Looks beautiful
Sagger-fired.
- Non-fired patinas are good for
sculptures: After
bisque apply MinWax, or
clear shoe polish.
- Use as underglaze with Low
fire clear glaze. Fire
to
Cone o6.
- Can be Raku-fired under any Raku
Clear Glaze.
Please contact
me if
you discover further possibilities. Thank
you.
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