These quantities may be weighed out and added to the dye-bath, or if solutions are kept, a calculation can be made as to the number of cubic centimetres which contain the above quantities, and these measured out and added to the dye-bath.
When all is ready, the bath is heated up, the swatch entered, and the work of the test entered upon.
Students are recommended to make experiments on such points as:—
The shades obtained by using various proportions of dye-stuffs.
The influence of various assistants—common salt, soda, Glauber's salt, borax, phosphate of soda—in the bath.
The influence of varying proportions of mordants on the shade of dyeing.
The value of various assistants, tartar, oxalic acid, lactic acid, sulphuric acid, on the fixation of mordants.
The relative value of different tannin matters, etc.
Each dyer should make himself a pattern-book into which he should enter his tests, with full particulars as to how they have been produced at the side.
It is important that a dyer should be able to make