It is unnecessary to give anything like a complete list of the pigments used to produce the colours and tints used by the house painter and decorator. A few of the most useful may, however, be mentioned.
It is not proposed to give a detailed description of them, but merely sufficient to distinguish those that are injurious from the others.
Many of these colouring pigments, such as the ochres, umbers, etc., are from natural earths; others are artificially made.
They may generally be purchased either in the form of dry powder or ground in oil.
Lampblack is the soot produced by burning oil, rosin, small coal, resinous woods, coal tar, or tallow.
It is in the state of very fine powder; works smoothly; is of a dense black colour when dry, and durable, but dries badly in oil It gives a greyish black colour to paint, as compared with the deep hue produced by vegetable black of good quality.
Vegetable Black is a better kind of lampblack made from oil. It is very light, free from grit, and of a good colour. It should be used with boiled oil, driers, and a little varnish. Linseed oil or turps keeps it from drying.1
Ivory Black is obtained by calcining waste ivory in close vessels, and then grinding. It is intensely black when properly burnt.
Bone Black is inferior to ivory black, and prepared in a similar manner from bones.
Blue Black and Frankfort Black of the best quality are made from vine twigs; inferior qualities from other woods charred and reduced to powder.
Grant's Black, or Bideford Black, is a mineral substance found near Bideford. It contains a large proportion of siliceous matter. It is denser than lampblack, but has not so much staining power.2
Prussian Blue is made by mixing prussiate of potash (Ferro-cyanide of potassium) with a salt of iron. The prussiate of potash is obtained by calcining and digesting old leather, blood, hoofs, or other animal matter with carbonate of potash and iron filings.
This pigment is much used, especially for dark blues, making purples, and intensifying black. It dries well with oil.
Slight differences in the manufacture cause considerable variation in tint and colour, which leads to the material being known by different names - such as Antwerp Blue, Berlin Blue, Haerlem Blue, Chinese Blue, etc.
Indigo is produced by steeping certain plants, from Asia and America, in water, and allowing them to ferment.
It is a transparent colour; works well in oil or water, but is not durable, especially when mixed with white lead.
Ultramarine was originally made by grinding the valuable mineral Lapis lazuli. Genuine ultramarine so made is very expensive, but artificial French and German Ultramarines are made of better colour, and cheaply, by fusing and washing, and reheating, a mixture of soda, silica, alum, and sulphur.
Cobalt Blue is an oxide of cobalt made by roasting cobalt ore. It is a beautiful pigment, and works well in water.
Smalt, Saxon Blue, and Royal Blue are coloured by oxides of cobalt.
Celestial Blue, or Brunswick Blue, and Damp Blue are chemical compounds (containing alum and other substances), which need not be described in detail.
Blue Ochre is a natural coloured clay.
Chrome Yellows are chromates of lead, produced by mixing dilute solutions of acetate or nitrate of lead and bichromate of potash.
This makes a medium tint known as Middle chrome. The addition of sulphate of lead makes this paler, when it is known as Lemon chrome, whereas the addition of caustic lime makes it Orange chrome of a darker colour.
The chromes mix well with oil and with white lead either in oil or water. They stand the sun well, but, like other lead salts, become dark in bad'air.
Chrome yellow is frequently adulterated with terra alba (gypsum).
Naples Yellow is a salt of lead and antimony, supposed to have been originally made from a natural volcanic product at Naples. It is not so brilliant as chrome, but has the same characteristics, and is very difficult to grind.
King's Yellow is made from arsenic, and is therefore a dangerous pigment to use in internal work. It is not durable, and injures several other colours when mixed with them. Chinese Yellow, Arsenic Yellow, and Yellow Orpiment are other names for king's yellow.1
Turners, Cossets, Verona, Montpellier, and Patent Yellow are all oxychlorides of lead; Cadmium Yellow a sulphide of cadmium.1
Yellow Ochre is a natural clay coloured by oxide of iron, and found abundantly in many parts of England.
It is not very brilliant, but is well suited for distemper work, as it is not affected by light or air. It does not lose its colour when mixed with lime as some other pigments do.
Spruce Ochre is a variety of the above of a brbwnish-yellow colour.
Oxford Ochre is of a warm yellow colour and soft texture, absorbent of both oil and water.1
Stone Ochre is found in the form of balls imbedded in the stone of the Cotswold hills. It varies in tint from yellow to brown.
Terra de Sienna, or Raw Sienna, is also a clay, stained with oxides of iron and manganese, and of a dull yellow colour. It is durable both in oil and water, and is useful in all work, especially in graining.
Yellow Lake is a pigment made from turmeric, alum, etc. It is not durable, and does not mix well with oil or metallic colours.1
Browns generally owe their colour to oxide of iron.
Haw Umber is a clay coloured by oxide of iron. The best comes from Turkey.
It is very durable both in water and in oil; does not injure other pigments when mixed with them.
Burnt Umber is the last-mentioned pigment burnt to give it a darker colour. It is useful as a drier, and in mixing with white lead to make stone colour.