Message: I am interested in learning more about the coloured vat dyes.  Which Procion MX dyes work best to overdye/discharge with which colours of vat dye?  Is there a chart available anywhere?  As I experiment, some definitely seem to work well, while others are duds.  I am predyeing cotton with an mx procion, then using itajime to resist areas, then overdyeing into a vat colour to discharge areas / and add more colour.  Do any vat dyes discharge/recolour each other?  Thanks so much for your help

The auxiliary chemicals for vat dyes, since they reduce the vat dyes to soluble form, can also reduce other types of dyes to remove some or all of their color. There are different recipes, with different reducing chemicals, but each of the different reducing chemicals should have similar results on the Procion MX or other fiber reactive dyes. (See What chemicals can be used to remove dye?, and compare them to the chemicals required for use with vat dyes in your recipe.)

If you're applying colored vat dyes onto fabric that has been dyed with Procion dyes, so that the color of the vat dye replaces the original color, then you will do best by starting with those reactive dyes that discharge most closely to white.

There are a few notes on which Procion MX dyes discharge best compiled into a chart on my page, "Which Procion MX dyes discharge the best? Which are good at resisting chlorine bleach?", in the rightmost columns. Ignore the columns on hypochlorite (bleach) discharge, since the results from bleach discharge are usually completely different from the results from reductive discharges. (You can't use bleach in place of the reductive discharge chemicals.) Here are the key points:

Premixed colors are likely to contain turquoise and/or fuchsia, so you should avoid proprietary mixed dye colors for this, and use only the pure single-hue fiber reactive dyes, or mix them yourself, so that you know which dyes your mixtures contain, and whether they are dischargeable.

I would like to see your notes on which Procion MX dyes have been working well for you in illuminating discharge, and which have been duds. Do they agree with the information I have here? (To convert to and from generic names from your dye suppliers' names, see my chart, "Which Procion MX colors are pure, and which mixtures?".)

In some cases, you might not find the Procion MX dyes to be ideal for discharging. There is another class of fiber reactive dyes that tends to be superior for discharge, the Remazol or vinyl sulfone dyes. They are easy to use, requiring only a little more warmth than Procion MX dyes, and can be used with the same recipes. The Remazol single-color black, reactive black 5, is unlike any Procion MX black, since it is not a mixture of several colors of dye; it is excellent for reductive discharge. You can buy reactive black 5 from PRO Chemical & Dye in the form of their Liquid Reactive Remazol dye; unfortunately, while Jacquard Products also packages a good line of Remazol dyes (which Dharma carries as the "Vinyl Sulphon" dyes), it does not include this excellent black, but instead a mixture of dyes that discharges relatively poorly. For more immediate gratification, you can often find "Dylon Permanent Black 12" at a Joann's fabric store or other crafts store; it is also reactive black 5, though the other chemicals included mean that you must follow the package instructions to use it, and it is less economical per use than the ProChem version.

For more information on discharging Remazol dyes, see:

Since all vat dyes share similar chemistry, not one of them can discharge another in the same way that they can discharge Procion or Remazol dyes. It's the thiox or dithionite in the vat dye mixture that does the discharging, not the vat dye itself. If you wish to discharge vat dyes, you must use an oxidative bleach, not a reductive discharge. Oxidative bleaches include chemicals such as chlorine bleach (hypochlorite) or sodium dichloroisocyanurate (used in swimming pools and also in Rit "Fast Fade for Jeans" or Dylon "Easy Bleach"), and they must be used in a completely different step from dyeing. You could, for example, draw on your vat-dyed items with a Clorox Bleach Pen, then rinse out, and neutralize the hypochlorite with Anti-Chlor or hydrogen peroxide, then wash thoroughly, before painting on another color of any class of dye.

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