Brentamine K is a
naphthol dye, also known as Fast Black K Salt or
2,5-Dimethoxy-4-[(4-nitrophenyl)azo]benzenediazonium chloride tetrachlorozincate. It is not as safe to use as (for example) Procion MX dyes. Its
MSDS indicates that it is irritating to the eyes, respiratory system and skin, and that there is some evidence that it causes cancer. I would not use this sort of chemical in the kitchen or any room where food is ever prepared or eaten; I'd use it only in a dye studio or chemical laboratory in which strict safety precautions are observed.
Brentamine (or brenthamine) Fast Black K Salt is described as turning any fiber reactive dye it comes into contact with into a darker brownish color: it "gives a subtle browning effect when used as a final dye over fibre reactive dyes" (wording seen at
www.candlemakers.co.uk and at
www.fibrecrafts.com). I'm not sure why just using a dark brown or black fiber reactive dye will not do as well, in most cases. Either way, you'll get a dark brown or black on top of the Procion dye, so why not stick to the safer category of dye? It's also described as turning indigo dye on fabric to an aubergine color, but this can be accomplished by using a dark red dye. The one possibly cool thing about the naphthol salt is that it does not (I think) change the color of the undyed fabric, so if you have a complex printed or painted design, made with fiber reactive dye or indigo, you can change its color while retaining the earlier design.
The way the diazo component of napthol dyes reacts does not require auxiliary chemicals (you need lye for the application of the other dyestuff used in naphthol dyes, the naphthol component, but that's not the stuff we're talking about here), and it does not require any heat at all. Unlike fiber reactive dyes, Brentamine Fast Black K Salt can be applied in a cold room or even at an icy temperature. So-called cold water dyes require the water to be at least a little warm, 70°F or over, but naphthol dyes do not require any warmth at all. You can apply it by hand-painting or by immersion. Looking at the instructions on the
Batik Oetoro web site, you might start with one tablespoon (6 grams) of the Fast Black K Salt in one cup (250 ml) of water. That's if you even want to mess with this substance in your own dyeing space; I wouldn't, since I'm dyeing in my home rather than a lab.
Paula
