Can baking soda be used as a fixative for dyeing?

Baking soda is the common name for sodium bicarbonate, NaHCO₃. It is chemically close to sodium carbonate, Na₂CO₃, which is commonly known as soda ash or washing soda, but its ability to increase pH is much weaker.

Uses with fiber reactive dyes

not for tie-dyeing at room temperature

Baking soda, or sodium bicarbonate, cannot be used as a substitute for soda ash for tie-dyeing at room temperature. While some reaction will occur, the resulting colors will be far weaker than if soda ash is used. This is because baking soda will not produce a pH above 8, while a pH of 10 or 11 works best as a fixative for fiber reactive dyes. Soda ash works much better.

good for dyes that will be steamed

In cases where fiber reactive dyes will be steam-set into the fiber, baking soda works well as a substitute for soda ash as a fixative. This is because sodium bicarbonate turns into sodium carbonate at high temperatures. Substituting baking soda for soda ash can be advantageous in delaying most of the dye-fiber reaction until steaming takes place. This method is most popular in painting with Procion H dyes, but will work with other fiber reactive dyes, too.

good for compromising on pH

Fiber reactive dyes will react with wool at high pHs, but a high pH will damage wool. Sometimes it is desirable to dye a blend of wool with a cellulose fiber in a single step, using fiber reactive dye such as Procion MX dye. Although the efficiency of the dye reaction is lower at a pH of 9 than at the ideal pH of 10.5, a singificant amount of dyeing will take place. You can use a combination of soda ash and baking soda to produce a pH of 9; a ratio of four parts baking soda to one part soda ash will be about right, depending on your water. Check the pH of this mixture with pH paper. Be sure that other factors, including temperature, time allowed for the dye reaction, and dye concentration, are all as good as possible, to make up for the lowered effiiciency of the compromise pH.

Uses with acid dyes

Acid dyes are normally used with a mild acid, such as vinegar or citric acid. Do not use baking soda at the same time as an acid, because the two will neutralize each other, cancelling each other out.

Converting sodium bicarbonate to sodium carbonate

If you cannot buy sodium carbonate anywhere (an unlikely problem in most countries), you can make your own sodium carbonate by heating sodium bicarbonate. Baking soda can be converted to soda ash by temperatures above 50°C (122°F), whether by steaming, boiling, or baking. To convert a quantity of baking soda to soda ash in your oven, place it in a glass baking dish and heat it, uncovered, for an hour at 400°F (200°C).

Where can you buy baking soda?

The ordinary baking soda you see at the grocery store is fine. Although baking soda, like soda ash, can be purchased from swimming pool suppliers, this is not usually more economical. Warehouse food stores, such as Sam's Club or Costco, are often the best source.

Don't invest in a huge quantity of baking soda. Baking soda has a shorter shelf life than soda ash, because some of the baking soda will gradually convert to soda ash in storage.

Do not confuse baking soda with baking powder. Baking powder is a mixture, used only in cooking, which contains baking soda, an acid such as tartaric acid, and a little starch. There is no use for baking powder in dyeing.