Yes, you can dye cotton.

More Info: Dye generally adheres well to cotton fabric especially if it is not treated. The best dyes to use for cotton fabric are reactive dyes or direct dyes. Reactive dyes work by forming a chemical reaction with the cotton fabric. Reactive dyeing offers good washfastness. With direct dyes, the dye molecules are entrapped within the structure of the fabric. This type of dye will bleed if the dye treatment is not immediately followed by a resin treatment.

The Home Dyeing Process of Cotton

You can use one of two dye processes for cotton at home-reactive or direct. Most home dye applications use a direct dye such as Rit®.  Though direct dyes do not adhere to cotton fabric as well as reactive dyes, they are most widely used because they are inexpensive, widely available, and easy to use.  The dyeing process simply involves dipping the fabric in a hot water solution of dye.

Because reactive dyes form a chemical reaction with the cotton fabric, the colors are brighter and they won't fade like direct dyes do. This dyeing process is more expensive and can be more complicated as many of the applications require additional fabric processes such as pretreatment with soda ash.

The Professional Dyeing Process of Cotton

Cotton fabric is dyed primarily utilizing two distinct dyeing processes-yarn dyeing or piece dyeing.

Yarn Dyeing-the yarn dyeing process involves dyeing the yarn before it is woven into fabric. This process is necessary when the weave is multicolored such as a gingham check or denim, which weaves blue and white threads together. During this process, yarn is wound on spindles and dye is pushed under pressure from the inside outward and then reversed to fully saturate the threads.

Piece Dyeing-Alternatively, piece dyeing involves dyeing an entire length of fabric at one time. During the piece dyeing process, a dry piece of fabric is immersed in a vat of hot-dye. It is then pulled and pressed between two rollers to extract excess liquid and distribute the dye evenly.