Citric Acid is a weak organic acid used as an acidifier in dyeing. It will alter the pH level of the dye bath and is an odourless alternative to white vinegar when immersion dyeing protein fibres such as silk and wool with Acid Dyes.
If you are painting or printing with Acid dyes, or using Procion MX dyes as an acid dye on protein fibres, and wish to steam or microwave set the dyes, the fabric should first be pre-soaked in a solution of Citric Acid and allowed to dry before painting.
The term “acid” in Acid dyes refers to the acidic conditions required in the dye bath rather than to the dye itself. The pH of the dye bath measures how acidic or alkaline the solution is and depends on how much acid has been added. We measure pH on a scale of 0 to 14. For hand dyers, lower numbers (closer to 0) indicate a more acidic dye bath, which is ideal for fixing Acid dyes to protein fibres such as wool and silk. Higher numbers (closer to 14) indicate an increasingly alkaline solution, which is required for dyeing cellulose fibres such as cotton with fibre reactive dyes.
Recommended pH Level
0.5% by weight of Citric Acid (i.e. 5g in 1 litre of dye bath water, or approx. 25g in 5 litres of water) gives a pH of 4.0. This is in line for Levelling Acid Dyes (the family of acid dyes sold by George Weil) where the recommended pH is around 4.0, and this acidity also works well for the other acid dye families, Milling and pre-Metallized.
As always this assumes that the water in the dye bath started at pH 7.0, which it may not, so testing with universal litmus paper is strongly recommended to ensure the correct acidity. This is equally true when using vinegar.
- pH 3 – 4 (Strong Acid): Target zone for citric acid or vinegar when dyeing protein fibres (wool, alpaca, silk).
- pH 7 (Neutral): Plain, untreated tap water.
- pH 10 – 11 (Alkaline): Target zone using Soda Ash for cellulose fibres (cotton, linen, hemp).
The post “Chemistry of Textiles and Dyes: pH” on Chemistry Art Blog explains further how the pH affects dyes.
Visit the Acid dyes section to view our full of range products.