MORDANT Cotouas.—The colouring matters of this class include some of the most important dyestuffs employed, since they furnish many See also:

• COLOURS, MILITARY

The wool is boiled for i to i a See also:

• HOURS, CANONICAL

One method is to impregnate the cotton with a solution of so-called " sulphated oil " or " See also:

• TURKEY

It is only successful, however, in the case of certain colouring matters and mordants, to some of which reference will be made in the following paragraphs. The Natural Mordant Colours.—It is interesting to note that nearly all the natural or See also:

• VEGETABLE

Crimson is dyed by mordanting the wool with alum and tartar and dyeing in a See also:

• SEPARATE

A brown on wool is obtained by first boiling for one to two hours in a decoction of the ground wood (5o%), and then boiling in a separate bath in solution of bichromate of potash (2 %) for See also:

• HALF

Wool is dyed in single bath by boiling with a mixture of Flavine (8 %), stannous chloride (4 %) and oxalic acid (2 %). Flavine is used in small quantity along with cochineal for dyeing scarlet on wool. Persian Berries are the dried unripe See also:

• FRUIT (through the French from the Lat. fructus; frui, to enjoy)

With chromium and aluminium mordants logwood dyes a dark blue, and even black; with tin, a dark purple; and with iron, black. The colours are only moderately fast to light. On wool the mordant is bichromate of potash; on cotton and silk an iron mordant is employed. Before use by the dyer the logwood is ground and aged or oxidized, by allowing moistened heaps of the ground wood to ferment slightly, and by frequently turning it over to expose it freely to the See also:

• AIR (from an Indo-European root meaning " breathe," " blow ")
• AIR, or ASBEN

In alizarin there are, for example, two characteristic hydroxyl groups (OH) occupying a special (ortho) position in the molecule, i.e. they are next to each other, and also next to one of the so-called ketone groups (C :0). In other Mordant Colours there are carboxyl (COOH) as well as hydroxyl groups, which are all-important in this respect. In addition to this, the general dyeing property is influenced by the constitution of the molecule itself, and by the presence of other side-groups, e.g. See also:

• NH2

Orange and Yellow.—Alizarin orange, alizarin orange G, alizarin yellow See also:

• PASTE (O. Fr. paste, modern pate, Late Lat. pasta, whence also in Span., Port. and Ital., from Gr. 1r&vrrl or 1raara, barley porridge, or salted pottage, ir&ao'ety, to sprinkle with salt)

In the older processes employed, the preparation of the cotton with oil was effected by passing the material several times through emulsions of olive oil and potassium carbonate solution; at a later date, and even now in the case of cloth, the cotton is first impregnated with hot oil (See also:

• STEINER, JAKOB (1796-1863)

On wool, the colour is so extremely fast to light and to milling that it may well serve as a substitute for alizarin. Alizarin Orange is employed in the same manner as alizarin. In wool-dyeing it is usually applied on chromium mordant for browns and a variety of compound shades in combination with other Alizarin Colours and dyewood extracts, less frequently on aluminium mordant. Galloflavin is used in wool and silk dyeing on chromium mordant as a substitute for fustic and other yellow dyewoods, to furnish the yellow part of compound shades. The alizarin yellows, R and GG, anthracene yellow, diamond flavine, chrome yellow, diamond yellow, carbazol yellow, chrysamine, &c., are Direct Colours with mordant-dyeing properties. They also serve as substitutes for fustic in wool or silk dyeing, and are dyed either on a chromium mordant, or first in an acid bath and afterwards saddened with bichromate of potash. Coerulein is employed in dyeing wool, silk or cotton with aluminium or chromium mordants, either as a self-colour or for compound shades. With aluminium mordant the colour is a moderately bright green, more particularly on silk; with chromium mordant, an olive-green. Coerulein S is the more soluble bisulphite compound of the ordinary coerulein. It is applied in the same manner, care being taken, however, to dye for some time (one hour) at a temperature not exceeding 6o° C. until the bath is nearly exhausted, and then only raising the temperature to the boiling point. Without this precaution coerulein S is decomposed, and the ordinary insoluble coerulein is precipitated. The colours obtained are very fast to light.

Fast Green, Dioxine and Gambine are chiefly of use in calico-printing and in wool-dyeing. With iron mordant they yield olive-greens, which on wool are extremely fast to light. Cotton is impregnated with ferrous acetate, dried, aged and fixed with silicate of soda, then dyed in a neutral bath. Wool is mordanted with ferrous sulphate and tartar (3 % of each) and dyed in a neutral bath. Acid Alizarin Green, Alizarin Cyanine Green and Diamond Green all dye wool direct in a bath acidified with acetic or sulphuric acid, and the dyed colour may be afterwards fixed or saddened with bichromate of potash, or they may he dyed on chromium-mordanted wool. The first method is very useful for pale shades, since the colours are very level or regular. Alizarin Blue is a dark blue dyestuff which, owing to the fastness of the colours it yields, has for many years been regarded as a worthy substitute for indigo in wool-dyeing. It is applied in the same manner as alizarin, the chromium mordant being alone employed. Alizarin blue S is the soluble sodium bisulphite compound of alizarin blue; it corresponds, therefore, to the above-mentioned coerulein S, and in its application the same precautions as to the temperature of the dyebath are necessary. The fastness of the dyed colours to light, milling and acid satisfy the highest requirements. Alizarin Cyanine, Anthracene Blue and Brilliant Alizarin Blue were discovered later than the above-mentioned alizarin blues, and, owing to their greater solubility and other advantages, they have largely replaced them as substitutes for indigo. They are dyed on chromium-mordanted wool, silk or cotton, and yield dark purplish or greenish blues, according to the particular See also:

• BRAND, JOHN (1744-1806)
• BRAND, SIR JOHN HENRY (1823-1888)

The fastness of the dyed colours to light, and general durability, are very satisfactory, but in fastness to milling and acids they are to some extent inferior to alizarin blue. Celestine Blue and Chrome Blue dye purplish blue and bright blue respectively, and are dyed in the ordinary way upon a chromium mordant. The colours they yield are inferior to the Alizarin Colours in fastness to light, but on See also:

• ACCOUNT
• ACCOUNT (through O. Fr. acont, Late Lat. comptum, cornputare, to calculate)

Alizarin Black is dyed on chromium mordant in the same manner as alizarin, and is used as a self-colour or in combination with other Alizarin Colours. Diamond Black is very useful for dyeing See also:

• GOOD, JOHN MASON (1764-1827)