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.
Calcium carbonate is lightfast. Like all carbonates, it reacts with strong acids
Calcium carbonate is completely non-toxic, and is used in many food, cosmetic, and pharmaceutical products. However, excessive consumption is not recommended.
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.
organic synthetic, quinacridone
Quinacridone Red is a high performance, transparent pigment with an average drying time and uneven dispersal. It is another name for Quinacridone Violet (PV19) and Quinacridone Red (PR192). Quinacridone pigments have relatively low tinting strength in general. For this reason, quinacridone colors are often expensive, because more pigment is required in the formulation.
Quinacridone Violet has excellent lightfastness and is considered the most lightfast organic pigment in this shade range.
Quinacridone Violet has no known acute hazards. Overexposure to quinacridone pigments may cause skin irritation. Quinicridone pigments contain a compound found to be a skin, eye, and respiratory irritant.
Although quinacridone compounds became known in the late 19th century, methods of manufacturing so as to make them practical for use as commercial pigments did not begin until the 1950s. Quinacridone pigments were first developed as coatings for the automotive industry, but were quickly adopted by artists.
Fe2O3 • H2O
Yellow Ochre provides artists with earthtones from cream to brown. It has good hiding power, produces a quick drying paint, and can be safely mixed with other pigments. Its transparency varies widely from opaque shades to more transparent ones, which are valued for their use as glazes. If gypsum is present, Yellow Ochre is not suitable for frescoing. (See Brown Ochre, PY43.) PY42 is made from synthetic iron oxides. PY43 is made from natural iron oxide.
Yellow Ochre has excellent permanence because ochres are some of the most permanent pigments available.
Yellow Ochre is non-toxic unless it contains manganese.
Ochre comes from the Greek word ochros, meaning pale yellow. It was one of the first pigments to be used by human beings, and evidence of its use has been found at 300,000 year old sites in France and the former Czechoslovakia.