Hi Paula. Namaste from Kathmandu Nepal.

I’ve bought and had brought over to me here some fiber-reactive dyes from Dharma Trading. Several of the other items needed don’t seem to be available in Kathmandu and I’m wondering about alternatives.
 
Salt—we have Himalayan salt which is not iodized and full of minerals. Will this do?
 
Fixative—we’ve got baking soda but I’m not sure of the others. Any thoughts?
 
Enzyme cleaner—we have these but no Synthrapol. Is this OK?

What an interesting question!

First, if you are dyeing cotton, linen, or any other cellulose (plant-based) fiber, it will work better at a pH about 10.5 or 11 than it will at baking soda's pH of about 8. Baking soda is sodium BIcarbonate, but, if at all possible, you want sodium carbonate, which produces a higher pH. Soda ash, or sodium carbonate, is the standard for dyeing with Procion type dyes, and should be the easiest of the high-pH chemicals to find. I can't imagine that you're surrounded by swimming pool stores (or by hardware stores with a swimming pool section); those are the best source of soda ash in warmer countries. Sodium carbonate must be in use somewhere in the country, though. It's an important ingredient in laundry powders, and an important cleaning agent in its own right. Look for a supplier to a water treatment plant, or to laundries. A common name for the decahydrate of sodium carbonate is washing soda. This will be perfect for your dyeing if you can find it.

If you cannot find sodium carbonate, you should look for another high-pH chemical. Caustic soda, or lye, is sodium hydroxide, a very high-pH chemical which you would use in dilute form. It's a little dangerous when you dilute it; always add a little lye at a time to water, rather than adding water to a container of lye. It will produce a significant amount of heat when it dissolves. Wear goggles or safety glasses, or even a plastic face shield (like welders wear) when working with undiluted sodium hydroxide. Be sure to have a quantity of water handy, to wash your eyes out with, or your skin off with, if an accident occurs. Sodium hydroxide is less convenient to use than sodium carbonate, because it can produce a wide range of pHs, so it matters if you use twice as much or half as much as you should. Sodium carbonate is much more forgiving as to the quantity used.

Another possible substitute for soda ash is trisodium phosphate. This is used, at least in the US, to wash down walls before painting them. It is between sodium carbonate and sodium hydroxide in its causticity. I buy mine from the local hardware store in the painting division, but nobody in the store can tell me whether they even have it, until I find the guy who specializes in paint.

When communicating about chemistry with people who do not speak your language (a common problem in research laboratories in the US), it is handy to know the chemical symbols used internationally by all chemists. The first four are all white powders, the fifth a liquid:

• Baking soda = sodium bicarbonate = NaHCO3; good for a pH of about 8
• Washing soda = sodium carbonate = Na₂CO₃; good for a pH of about 11
• Caustic soda = lye = sodium hydroxide = NaOH; good for a pH of up to 14, but may be diluted to 11 or  10 or 8
• TSP = trisodium phosphate = Na₃PO₄; good for a pH around 12
• Water glass = sodium silicate = Na₂SiO₃. Sodium silicate is usually purchased as a liquid solution with a pH about 11.3.

By the way, if you see potassium instead of sodium in any of the above chemicals, go for it; it will not be significantly different from sodium. The chemical symbol for potassium is K, e.g., potassium carbonate is K₂CO₃.

You can see more information on these various high-pH chemicals on my page about soda ash, and you can ask me for further advice after you've obtained whichever high-pH chemicals you can.

Another very useful fact is that sodium bicarbonate decomposes to sodium carbonate when heated. This is actually a perfectly practical way for you to get soda ash, given that you have baking soda. Doug Wilson posted this advice to the DyersLIST mailing list: "Put the dry baking soda in shallow layer in a glass dish and put it in the oven at about 150°C (about 300°F) for half an hour - it will be converted to sodium carbonate." Do not use a metal pan to hold your sodium bicarbonate when converting it to carbonate; aluminum in particular will react badly with the carbonate, but so will any bare metal, such as cast iron or copper. You can store this sodium carbonate at room temperature for a long time, preferably sealed in plastic to prevent hydration from the humidity in the air. Hydration will not harm the soda ash, as it converts it from the anhydrous (dry) form to the form found in washing soda, which just makes it heavier so you have to use more for the same effect. It hardly matters since sodium carbonate works well even if you do not use quite the right amount.   

Onto the salt question. I don't like the use of additional minerals, because some will interfere with dyeing. Iron will make your colors dull and drab. Iodine in the salt is okay; it's added in a sufficiently small amount to not really matter, and iodine does not seem to react with the dyes. Everyone says to use non-iodized salt, but iodized salt will work. Other minerals such as alum, copper, tin, and chromium all have different effects on the colors of dyes, which is why they are used to alter the color of natural dyes (and, as mordants, to help bind natural dyes to the fiber). Calcium and magnesium are hard-water chemicals that cause particular problems, because they will create insoluble soap scum, which can act as a physical barrier between dye and fiber. Calcium can also create difficult-to-wash-out complexes of unfixed dye which cling to the fiber although they have not properly bonded; these gradually come out as the fabric is washed, creating an appearance of inadequate washfastness.

You don't have to use salt for direct dye application or low water immersion dyeing, but it helps tremendously in dyeing solid colors in high-water-ratio immersion dyeing, in a bucket or washing machine. Without it, you will waste quite a lot of dye.

Calcium and magnesium in the water are common problems in many places around the world. If you have hard water, you have calcium and/or magnesium in it. These ions in your drinking water are very healthy for you to drink, but they are not so good for dyeing. If your water is very hard, you will need a water softener, or else to use distilled or de-ionized water. The water softener we dyers like best is sodium hexametaphosphate, (NaPO₃)₆. You only need a teaspoon or so to mix with each recipe of your dyes. If the water is very hard, you need to add it to the washing machine or basin as well. This chemical is also called Calgon or Calgon T, but beware of the Calgon-brand liquid water softeners, which contain polycarboxylates, instead, which are said to interfere with dyeing. Buy only the powdered Calgon. PRO Chemical & Dye calls this chemical MetaPhos, and Dharma Trading Company sells it as Water Softener. If, when you mix your soda ash into water, it seems to form an insoluble white precipitate, that is the calcium or magnesium, and it can interfere with dyeing. If it's bad, and if you can't find sodium hexametaphosphate, try to use distilled or deionized water for mixing your dyes and dyebaths.

As far as detergent is concerned, don't worry about it. Although Synthrapol is very nice to use, whatever laundry detergent you have should work, as long as you rinse out the dye in cool water without detergent, before using the hot water necessary to remove the unattached excess dye. Always make sure to allow an excess of reaction time for your dye to bond to your fibers first. If you think it will take six hours at a certain temperature, leave it overnight. (Be sure it's warm enough, 70°F or warmer.) This will allow any dye that has not reacted with the fiber to react with the water, so that no active dye will remain to cause permanent backstaining. Once dye has reacted with the water, or hydrolyzed, any stains caused by dye transferring from one part of the fabric to another can be washed out with sufficiently hot water.

Good luck with your dyeing. I'd love to hear more about it. Please consider joining the Dye Forum (it's free).

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