Tie-dyeing

The basic process is to tie up the material before applying dye in such a way that the dye only reaches part of the area to which it is applied. The boundaries of the dyed and non-dyed areas are usually rather blurred, as the dye has begun to soak into the non-tied sections.

During tie-dyeing, if a good fiber reactive dye is used, a chemical reaction takes place which permanently bonds the colorful dye to the fabric, making tie-dye safe to wash amongst other, non-tie-dyed clothes once the excess dye has been removed. As the name suggests, the fabric is tied, usually with string or rubber bands, after being folded into a particular pattern. Some areas, where the textile is tied and in inner parts of folds, do not absorb dye as readily, forming a pattern. This is known as a resist technique (the areas that are tied and the inner parts of folds resist dyeing).

Patterns are also formed by applying different color dyes to different sections of the fabric. The folded and tied textile is usually first submerged in a bath of soda ash solution for 5-30 minutes to prepare it to take the dyes, which may be applied while the fabric is still wet with this solution, or once it has dried. Soda ash, which has a high pH, prepares the cellulose fibers of the cloth for permanent chemical bonding with the acidic fiber-reactive dye used in tie-dyeing. Dye is then applied, either by submerging the cloth bundle in a bath of dye or by squirting dyes onto specific areas of the fabric.

Alternatively, the soda ash may be added directly to the dye solution rather than soaking the textile in a solution of soda ash. With this technique the dye must be used within about two hours as the soda ash within the dye solution will react with the dye. In another variation, the fabric may be dyed, and then immersed in soda ash solution.

After 12-48 hours, depending on temperature, dye, and the desired brightness of the final product, the fabric can be unwrapped and rinsed. After working out the excess dye under running water, tie-dye should be washed in a washing machine. A detergent called Synthrapol is preferred by many dyers, although any neutral detergent may be used. Excessively alkaline detergents may cause back staining.