Color Swatch created using heavy to light application and was applied on 100 lb (163 gsm) drawing paper material.
This color contains the following pigments:
PW18—Calcium Carbonate
Pigment Type
inorganic
Chemical Name
calcium carbonate
Chemical Formula
CaCO3
Properties
Calcium carbonate, the mineral constituent of chalk, is a low tinting strength, inexpensive white pigment that is often used is a buffer and filler. Because of its low tinting strength, it is overwhelmed by other colors. It is used in gesso and other coatings to give the surface more tooth, a desirable characteristic for some painting techniques.
Permanence
Calcium carbonate is lightfast. Like all carbonates, it reacts with strong acids
Toxicity
Calcium carbonate is completely non-toxic, and is used in many food, cosmetic, and pharmaceutical products. However, excessive consumption is not recommended.
History
Naturally occuring chalk deposits have been mined since prehistoric times. Rocks and minerals that contain calcium carbonate include aragonite, calcite, vaterite, chalk, limestone. marble, and travertine. Calcium carbonate is the principle component of lime, used in many agricultural and industrial applications.
Alternate Names
Chalk
PG17—Chromium Oxide Green
Pigment Type
inorganic
Chemical Name
chromium oxide
Chemical Formula
Cr2O3
Properties
Chromium Oxide Green is a dull, dense, willow or pale green color that is completely opaque. It has an average drying time and a low tinting strength. It is fairly flexible in oil form and is suitable for all purposes and mediums. This pigment is less versatile in mixtures than Viridian and Phthalocyanine Green, but mixes well with other colors without overpowering them.
Permanence
Chromium Oxide Green has excellent permanence, even at high temperatures.
Toxicity
Chromium Oxide Green is slightly toxic. Evidence of Chromium(III) carcinogenicity is inconclusive. Chromium(III) salts appear in greenish pigments such as PG17. Chromium(VI) salts, which appear in yellowish pigments, have been proven to cause cancer.
History
Louis-Nicolas Vauquelin discovered the element chromium in lead chromate in 1797. It began to be used as an enamel and ceramic color in 1809, but it had limited use as a pigment until 1862, because of its cost. It is the most commonly used green for military camouflage because it appears the same shade as living foliage under infrared light.
Alternate Names
Chrome Oxide Green, Olive Green, Permanent Green. Varieties of Chromium Oxide Green include Arnaudon's Green, Dingler's Green, Plessy's Green, and Schnitzer's Green.
PW20—Mica
Pigment Type
inorganic
Chemical Name
aluminum silicate
Chemical Formula
H2KAl3(SiO4)3
Properties
An off-white pigment with complex reflective effects, mica is often used with transparent pigments to create mixed pigments with interference and pearlescent effects.
Permanence
Mica is permanent and lightfast.
Toxicity
Although it is completely non-toxic and not bioreactive, fine particles may be irritating. This is of concern primarily for those exposed occupationally to dry mica powder. Breathing mica particles may cause lung fibrosis and pneumoconiosis.
History
Mica has been used as a pigment since prehistoric times.
Alternate Names
n/a
