Phthalo Blues are pure and clean primary blues with superior covering power. They have a very high tinting strength and tend to overwhelm other pigments, but if color strength can be controlled, they make predictable mixed colors. In oil form, blues are very deep and slow drying. When mixed with other colors or if chlorine is added, Phthalo Blue quickly tends towards green. When using alone, mix with some white, as Phthalo Blue can be semi-transparent and almost black on its own. It is among the most compatible of modern colors with mineral colors and is considered more reliable than Prussian Blue, while sharing the same physical and color properties. Phthalo Blue is a good color for glazing.
Phthalo Blues are completely lightfast and stable and are permanent for all paint uses. They are currently used in inks, coatings, and many plastics due to their stability and are considered a standard pigment in printing ink and the packaging industry.
Phthalo Blues have no significant hazards, although those made before 1982 contained some PCBs (polychlorinated biphenyls).
Developed by chemists using the trade name Monastral Blue, the organic blue dyestuff now known as Phthalo Blue was presented as a pigment in November 1935 in London. Its discovery was accidental. The dark color was observed in a kettle where a dye was being made from a British dyestuff plant. The demand for such a pigment came from commercial printers who wanted a cyan to replace Prussian Blue.
Lamp black is a very opaque, heavily staining black pigment that does not have much covering or tinting power. It is typically the most opaque black in watercolor form. Though a very pure black, it tends to muddy slightly in mixtures. Natural sources may be brownish or bluish in tone because of impurities. When used in oil paints, it is one of the slowest drying pigments, and should not be used in underpainting or applied in layers underneath other colors.
Lamp Black is very lightfast and absolutely permanent. It is used in all techniques in permanent painting.
<p>Carbon itself is not considered hazardous, however other combustion products that are hazardous are often present as impurities when Lamp Black is produced from natural materials. For this reason, commercial preparations of the pigment should be considered slightly toxic. Avoid skin contact and inhalation. Where such impurities are present, Lamp Black is a possible human carcinogen.</p>
Lamp Black is a carbon based black traditionally produced by collecting soot (known as lampblack) from oil lamps. It has been used as a pigment since prehistoric times. It is the black found in Egyptian murals and tomb decorations and was the most popular black for fresco painting until the development of Mars Black.
Dioxazine Violet is transparent and has very high tinting strength. It is a staining pigment, very dark valued when it is used at full strength. Concentrated, it paints out nearly black, but it mixes with Titanium White to form bright, opaque tints of purple. PV23 produces slightly redder shades than PV37. Because the hue can vary with the conditions of preparation and grinding, it may be offered in red shade, blue shade, and so forth.
Dioxazine Violet has good lightfastness. There may be some concern about it fading or shifting in color in tints and washes. Some artists have reported that PV37, a molecular variant, is more lightfast than PV23.
Two molecular variants of Dioxazine Violet, PV23 and PV37, are available. They have similar properties, but mix slightly differently.