One of the most important tools, in this particular process of hand dipping - or "mottled" dyeing - is a set of gloves and liners that protect your hands (as you plunge the fabric into the boiling acid dyestuff).
Acid Dyes will be used for this process. Acid dyes are used to dye protein fibers such as woolen goods, soy protein fibers called Soy Silk, and the synthetic polyamide fiber nylon. They produce a very even, single-color solid effect. Either vinegar or diluted acetic acid can be used to set them.
Acid dyes can safely be dissolved in hot or even boiling water without making them go bad but you must be very careful to completely dissolve the dye. I often add a drop of a surfactant, such as synthrapol, to aid in the dissolution. Another method is "pasting" the dye: mix a very small amount of water with your dye and stir it until it forms a smooth paste. Gradually add more water, stirring until smooth, and only then mix in the rest of the water.
The dyestuff is brought up to a rolling boil, and I mean hot! The warm/wet fabric, in this case the woolen pants, will be bunched up and plunged into the boiling dye, held there for 12 to 16 seconds. This will be repeated over and over with different color dye-baths until the layered and mottled color effect has been achieved.
The wool pants in their pristine state. I have not slit the button holes, the back has been left open and they are unhemmed.
Halfway through the process (it is lengthy), the color is starting to build up on the pants.
I intentionally sewed these pants with a polyester thread that does not take in the dyebath. The stitching adds a contrast note to the overall effect, plus it is strong and will hold the garment together better than a natural thread would.
Pants are pressed and readied for shipping.
The idea is that they should look just like the rendering!