Gloria may be in one colour only, a self-colour as it is called; this case is comparatively simple, the only care that is required being to select dyes which have an equal affinity for the two fibres or which give but slightly different shades. Still, some good effects are obtained when dyes are used which dye the silk and wool different colours but give the combined effect of a self-colour. Or the fibre may be purposely dyed in two different colours in some cases to give the "shot" effect. This is much more troublesome, but with a little care can be carried out with good results. The dyes available for dyeing gloria may be classified, according to their behaviour in regard to their dyeing of the two fibres, into three groups as follows:--
Group A.--Those which will dye the two fibres of equal shade.
Group B.--Those which will dye the wool at boiling heat more readily than the silk.
Group C.--Those which will dye the silk only in a cold bath.
Group A consists of those dyes which can be used in dyeing self-colours on gloria from acid baths. It includes Alkali Blue, Naphthylamine Blacks, Naphthol Green B, Indian Yellow, Croceine A Z, Croceine Orange, Orange R, Brilliant Croceine M, Rose Bengale, Thiocarmine R, Soluble Blue, Formyl Violet S 4 B, Acid Green, Croceine Orange G, Carmoisin, Acid Violet 5 B, Fast Acid Violet 10 B, Fast Green Bluish, Rhodamine, Silk Blue, Victoria Black, Archil, Turmeric, Safranine, Auramine, Quinoline Yellow, Azoflavine, Victoria Blue and Bismarck Brown.
Group B comprises those dye-stuffs which in a boiling acid bath dye the wool deeper than the silks, in other words have more affinity for the wool than the silk, Tropæoline O, Acid Magenta, Indigo Extract, Phloxine, Naphthol Yellow, Orange G G, Scarlet S, Azo Red A, Eosines, Thiocarmine R, Naphthol Black B B, New Victoria Black Blue, Erythrosine, and Roccelline.
The silk becomes tinted to a more or less extent when in such a bath, but often the colour is readily removed either by subsequent passage through boiling water or through hot soap liquor. A very good clearing can be effected by the use of a bath of acetate of ammonia. Naphthol Yellow, for instance, only imparts a very faint shade of yellow when thus dyed, and this is easily removed by boiling-water treatment.
Group C.--Those dye-stuffs which will dye the silk more readily in a cold bath than the wool. These comprise most of the basic dyes, such as Thioflavine T, Safranine, Brilliant Green, Methyl Violet, Magenta, New Methylene Blue, Bismarck Brown, Rose Bengale, Phloxine, Acid Greens, Formyl Violet S 4 B, Rhodamine, Solid Blue, etc.
Gloria may be dyed either by a one-bath or two-bath process, and either one or two colours, as may be required. In both cases advantage may be taken of the different affinities of the two fibres for the dye-stuffs used, as, for instance, the silk may be dyed brown, the wool olive by using a mixture of Acid Yellow, Indigo extract and Orange G. Indigo extract, Cochineal, Acid Magenta, Picric acid, Naphthol Yellow, and Tartrazine dye the wool only at the boil.
The following recipes will serve to illustrate the foregoing remarks and show how this important fabric may be dyed:--