The Natural Organic Colouring Matters
By
Arthur George Perkin, F.R.S., F.R.S.E., F.I.C., professor of colour chemistry and dyeing in the University of Leeds
and
Arthur Ernest Everest, D.Sc., Ph.D., F.I.C., of the Wilton Research Laboratories; Late head of the Department of Coal-tar Colour Chemistry; Technical College, Huddersfield
Longmans, Green and Co.
39 Paternoster Row, London
Fourth Avenue & 30th Street, New York
Bombay, Calcutta, and Madras
1918
Kaikki kuvat (kemialliset kaavat) puuttuvat // None of the illustrations (of chemical formulas) included.
THE dyestuffs of this small group, Sanderswood, Barwood, Caliaturwood, Camwood, and Narrawood, all possess very similar dyeing properties, and owing to the sparing solubility in water of the resinous colouring matters which they contain, they are called "insoluble red" woods. They cannot, therefore, be made to yield the same type of commercial extract as is given by the soluble red woods, Brazilwood, Sapanwood, etc.
These dyewoods are chemically interesting in that the colouring matter present is substantive to wool, and thus, by merely boiling the material in an aqueous extract of the wood, or in a bath containing this in suspension, a brick-red shade is produced. It is remarkable, however, that though the tinctorial constituents of all these woods are readily soluble in alcohol, that the dye cannot now be removed from the fibre by this solvent, and it thus seems probable that it may exist thereon in the form of an acid calcium salt. Thus only by previously steeping the wool in concentrated hydrochloric acid, and subsequently washing, can the colouring matter be extracted by alcohol. The shades given by sanderswood, barwood, and caliaturwood are of a very similar character, camwood, on the other hand, giving somewhat bluer tones, and again according to dyers its colouring matter is more readily dissolved by water than that of the other dyewoods of this class.
Camwood
Chromium - Red-violet
Aluminium - Red
Tin - Blue-red
Iron - Violet
Sanderswood
Chromium - Brown-red
Aluminium - Orange-red
Tin - Red
Iron - Maroon
Though now practically unemployed in cotton dyeing, these woods, and especially barwood, were used considerably at one time in the production of a "mock Turkey-red". For this purpose the material was mordanted with a tin mordant, employing either stannate of soda or stannic chloride, and subsequently tannin or sodium carbonate as the fixing agent. On dyeing with barwood, a good bright red colour was thus produced, fast to milling but somewhat fugitive to light.
In wool dyeing, these woods still find a moderate application, usually in conjunction with other dyewoods, such as logwood and fustic, for the production of compound shades, and to a slight extent as a "bottom" in indigo dyeing. The general method of dyeing with them consists in first boiling the wool in a bath containing the wood, and then subsequently adding a solution of either potassium dichromate, ferrous sulphate or copper sulphate, the first operation being known as "stuffing" and the second, in which the shade becomes much browner, "saddening".
The colours given by these dyewoods are somewhat fugitive to light, and thus they have been almost superseded by the alizarins.
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