The Red and Yellow colors are distinctly less satisfactory. None of them can really be considered better much than third class. Of the Reds the best is probably the color known as Safranine, different brands of which, giving as a rule the yellow shades, are manufactured by the various color houses; one brand being about as fast as another. For the bluish shades of red, probably the fastest is Diazine Red, (Kalle).
As regards Yellow, the list is even more unsatisfactory.
There is a very beautiful golden yellow, known as Auramine O, manufactured by most of the color houses, which, however, is hardly fast enough to be in the third class. This dyestuff, by the way, is injured by boiling, and therefore should never be used in a dye-bath heated to over 130° or 140° Fahrenheit. Less pleasing in shade, but somewhat faster to sunlight, are the rather orange or brownish yellows known as New Phosphine G (Cassella), and Methylene Yellow (Metz). Somewhat brighter colors, though less fast to light, are produced by Thio flavine T. None of these, however, compares in fastness to the selected colors of any other class in this book.
The various brands of the common dyestuff, Bismarck Brown, are largely used for leather, and while probably inferior in fastness to any of the colors mentioned above, are not found in commercial practice too fugitive to be pretty satisfactory. When, however, materials are liable to be exposed for any length of time, two or three weeks in succession, to direct powerful sunlight, it will generally be advisable to use mixed browns made from fast Acid colors.
Upon the whole, although we are still frequently called upon to employ them, they must, from the craftsman’s standpoint, always be considered as untrustworthy. They should, therefore, never be used where dyestuffs of any other class can be made to take their place.
DYEING DIRECTIONS
The application of Basic colors to leather dyeing will be discussed later. We shall now discuss their application to basketry materials, such as straw, raffia, willow, and the like, where they will be found useful.
It will at once be noticed that these dyestuffs are far more powerful than any thus far met with in these lessons. Indeed, while there will be needed, for full shades of the Vat colors, pastes from about 15% to 20% of the total weight of the dry materials, of the Sulphur colors from 7% to 10%, of the Salt colors from 4% to 6%, and of the Acid colors from 1½% to about 3%, most of these Basic colors will give very full shades with from ½% to 1% of the total weight of dry material.
These Basic colors do not dissolve readily in water, but are easily soluble in alcohol, and also in even very dilute acids. Acids form salts with the dyestuffs and these salts dissolve when the free coloring matters do not. Accordingly the Basic colors should always be dissolved carefully in a separate cup or vessel, using hot water, and adding, for each spoonful of dyestuff, two or three spoonfuls of acetic acid or, if more convenient, of strong vinegar.
The color, thus dissolved, should be added to warm water in the dye-pot, preferably through a fine strainer or piece of cheesecloth, to avoid any undissolved particles which would cause spots. The well-wetted goods are immersed in this dye-bath, and turned, either in the cold or with gentle heat, until the desired shade is reached, or the bath is exhausted. The material is then taken out, rinsed once or twice in water, cold or warm, carefully dried, and, if necessary, straightened and pressed or ironed out.