Name: Mark
Message: Hi Paula,
Love your website. I have been experimenting with low immersion dying of rayon/silk velvet. The results have been good, however I notice that i have much more dye to rinse out with deep saturated red and blue than any other colour. Earth tones like olives/rust/brown/gold/grey all rinse out with 2-3 rinses. The red and blues need at least 12 rinses until water is clear. I'm using Procion MX (G&S #502 Slate Blue + #412 Red) with a chemical water made up from urea & some calgon and adding sodium carbonate just before applying the dye (no salt!). I'm letting the finished piece dry and steam setting for 1/2 hr. I let air set for 48hrs and then rinse. Is the excess amount of dye rinsing out a factor of the dye composition or is it something I am doing/not doing? Many thanks,

All MX dyes have a poor rate of exhaustion. There is always a lot of dye to rinse out afterwards, quite unlike the experience of dyeing wool. There will be more dye to rinse out if the dye batch is older, so that an excess must be used to make up for dye that has already reacted with the moisture in the air. It is critical to rinse the dyed items in cool water first (95 degrees F. or less), before washing in hot water to remove the last of the unreacted dye, as an initial rinsing with hot water can cause unattached dye to loosely associate with the fiber, making it far more difficult to rinse out. It is much more efficient, after the initial cool water rinsing, to let the dyed items soak in hot water for a while, rather than just quickly rinsing with it. I assume that you are using Synthrapol or its equivalent to wash out the dye. Ordinary detergent can be used, though it may be less efficient, but the first rinsing must be free of high pH detergents. Synthrapol and its equivalent are of neutral pH and are optional during the initial cool water rinse; they may help to prevent dyes from redepositing on other parts of the fabric.

An interesting fact is that the properties you note for certain colors are not found for all dyes of those colors in a given dye class. For example, red MX-8B (fuchsia) is MUCH faster reacting than red MX-5B (it is faster than all of the other Procion MX dyes, in fact). Choosing a different red and a different blue, unless they are mixtures made with the same individual dyes, will change everything. Some experienced dyers say that they get much richer colors if they dye the same piece of fabric twice, rather than using a lot of dye only once. Thin silk, such as the backing of rayon velvet, tends to have only a limited number of dye sites, however.

G&S Slate Blue is an unmixed dye, Procion blue MX-2G. There are several navies in the Procion MX line of dye, but I don't think G&S carries them. For example, ProChem carries blue MX-4GD as their #414 deep navy. I believe that #412 red is a mixture of other colors, possibly a mixture of either 405 hot pink or 408 fuchsia with an orange.

One way to help the yield from an MX dye is by increasing the reaction temperature. Ideally, this should be between, say, 80 and 105 degrees Fahrenheit (27 and 41 Celsius). Sometimes, in LWI, I will fill my sink with hot water and rest my buckets in it for a few hours. Your steaming should take the place of this step very well, however. It is unnecessary to steam silk or rayon, when dyeing with MX type dye and soda ash, if you allow enough time at a warm, not hot, reaction temperature. Steaming is required with this dye only when acid dyeing silk, using acid instead of soda ash. (Rayon cannot be dyed under acid conditions.) Urea is not necessary or useful in low water immersion dyeing, but salt can actually be quite useful in increasing the crystalline patterning of LWI. Use up to one teaspoon (5 ml) of ordinary non-iodized salt per cup (250 ml) of water. Add it only after dissolving the dye, as salt reduces the solubility of dye. I like to add the soda ash last. This is something you may want to experiment with someday.