Name: Rachel
Message: I was wondering if you know if Procion dyes are considered "green"? By that I mean, does the excess dyeing liquid damage the environment once it's washed down the drain? I'm planning to dye some organic cotton and don't want to waste all the efforts that went into making the fabric, without harming the environment, by dying it with something that will. Thank so much!

Procion MX dyes are often described as "eco-friendly", whatever that really means. (I suspect that it frequently does not mean very much.)  They are certainly less damaging to the environment than the heavy metals used with some other types of dye, such as the hexavalent chromium used with chrome dyes for wool. They will do no harm to your septic system, if you have one. When spilled on the ground (for example, from tie-dyeing in the yard), they lose their color on the dirt within a few days, apparently as the result of being broken down by soil microbes. However, the textile industry produces vast amounts of waste water from dyeing fabrics, so even relatively innocuous dyes can be a problem when used in vast quantities in a mill. I've seen references to many papers about using various microbes to decolorize wastewater from industrial dyeing.

The primary problem with Procion MX dyes is the amount of water that is required to wash out excess or hydrolyzed dye, which has not attached to the fiber. In cases of water shortage, this could be a major problem. It's also a problem for large mills, which must treat their waste water before disposing of it. At home, you can reduce the amount of water needed for rinsing by soaking the fabric for some time in very hot water, as part of the washing-out process. Be sure to start with a cool water rinse.

Some people have concerns about heavy metals. The EU Eco Label requires that dyestuffs not contain more than 250 ppm copper. The metal found in some Procion MX type dyes is much less of a problem than the more toxic mordants that are often used with natural dyes. (Among mordants for natural dyes, alum is not bad, but tin and chromium can be quite harmful.) Many of the Procion MX type dyes are metal-free, but others may contain small quantities of metal ions. For example, the very popular Procion Turquoise MX-G contains copper, perhaps 1 to 5% by weight, while rubine MX-B also contains copper. The amount of metal is insignificant when used in the small quantities you might use at home. The information I have handy indicates that these Procion MX dyes do not contain metal in their chemical structures: blue MX-R, blue MX-G, red MX-5B, red MX-8B, and yellow MX-8G. (To translate these to the names used by your dye supplier, see the chart at Which Procion MX colors are pure, and which mixtures?.)

One thing I like about Procion MX and other reactive dyes is that fabrics dyed with them, after the unattached dye has been removed, do not bleed when wet, unlike direct dyes; this means that I think that the dye is much less likely to transfer to the skin of a person wearing a garment dyed with them. Unlike direct dyes, they do not require a cationic dye fixative, which may contain formaldehyde. Taken together, these facts means that the dyed items made with Procion MX and other reactive dyes are probably among the safest for use on babies or by people with sensitive skin.

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