Name: Timmy

Country: Malaysia

Message: I have hand-painted a piece of batik. The piece is supposed to be just hung on the wall without any contact with water, but I want to make it a step further, that is fixing the colours. I asked the person handling the batik-painting, and she told me it can be fixed using Sodium Carbonate, as mentioned on this website. But I want to know: what is the ratio of Sodium Carbonate to water that I need to use to effectively set the colours? 5ml (dissolved) to 250ml? Also, how much salt do I need to use to maximise colour retainment?

In batik, the dyes are usually fixed at the time that they are applied. Trying to fix the dyes after the wax has already been removed may result in dyes smudging into areas of the design where they are not wanted.

Sodium carbonate can be applied to the fabric (cotton, silk, or rayon) before the dye, as in the standard tie-dyeing recipe. It can also be mixed with the dyes immediately before they are applied. Unfortunately, when it is applied after the dyes, the dyes tend to run together a bit in the water the sodium carbonate is dissolved in. Would this ruin the effect of your batik's design?

Do you know for sure what kind of dyes were used in your batik? If not, it's difficult to tell whether trying to after-fix the dye will even work. Sodium carbonate is used with fiber reactive dyes , but not with direct dyes, acid dyes, or naphthol dyes. Some fiber reactive dyes can react with natural fibers at relatively cool temperatures; Procion MX dye, for example, works well at temperatures as low as 21°C (70°F), though warmer is better. Some other fiber reactive dyes will not work at room temperature and require steaming to set the dye, even in the presence of sodium carbonate; Procion H and Procion HE are among the dyes that have this requirement.

If having the colors run together will not be a problem for you, then you can soak your batik in warm water with sodium carbonate dissolved in it, or spray the sodium carbonate mixture on. Anywhere from 3 to 5 ml (one-half to one teaspoon) per cup (250 ml) is a good concentration. Salt is not needed for dye fixation, for dyes that are applied directly, as in batik. However, the fact that salt reduces dye solubility can be useful. If you add as much salt as can possibly dissolve in water to your sodium carbonate mixture, it will reduce the amount of dye that comes off of your batik into the sodium carbonate solution. You can dissolve almost 90 grams of sodium chloride in 250 ml of water. If your water supply is hard, that is, if it contains calcium and magnesium ions, it is best to use distilled water or chemically softened water, or to add a water softener, sodium hexametaphosphate, to the water you will be mixing your sodium carbonate in.

Alternatively, you can use sodium silicate solution as an after-fix treatment, instead of sodium carbonate. This is popular enough that one dye supplier in the US sells sodium silicate solution under the brand name 'AfterFix'. Common names for sodium silicate solution include Water Glass, Soluble Glass, Silicate of Soda, or Egg Preserver. If you can find sodium silicate solution, I'll be glad to share information on how to use it (or you can study the instruction sheets at ProChem [PDF] and Dharma).

I believe that sodium silicate would be preferable to sodium carbonate for your purposes.

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