Replies

1. 
   stancalow | Mar 30, 2002 06:39pm | #1

   I think that the commonly used dyes used to be based on "aniline"  as you described, but that the term has become a generic term for a newer family of chemical dyes that do not contain aniline.  Somebody correct me if I am wrong. 

2. 
   RickL | Mar 31, 2002 02:08am | #2

   Get the MSDS sheet from the retailer.

3. 
   JBJewitt | Mar 31, 2002 06:29pm | #3

   This question is a good one, and one that comes up frequently. I'd like to take a bit of everyone's time to clear this up, at least for the folks who read KNOTS.

   The term aniline comes to us from the original synthesized dye, mauveine, created by a young English Chemist (William Perkins) in the 1850's. He reacted nitric acid and aniline with potassium dichromate. Strangely enough, he wasn't looking to make a dye, rather a synthetic form of quinine to treat malaria. The bluish, water-soluble colored precipitate he got at the bottom of the flask obviously wasn't quinine, but he had the foresight to see commercial potential for it. So he set up a large company with his father to make the stuff, and arguably ushered in the era of organic chemistry, due to the fact that most chemicals synthesized up to then had little or no commercial value.

   These dyes and the ones that followed came to be known as aniline dyes and coal tar colors. Coal tar is the raw material from whence they got aniline. Over the years that followed, many other chemical syntheses followed, notably the azo dyes, which eventually gave birth to the chemistry that we use to get most of the synthetic dyes and pigments that are used in woodworking.

   Aniline unfortunately remains firmly imbedded in the commercial world of making and marketing synthetic dyes. For example the "A" in the company called BASF stands for aniline. "Aniline dyed, top-grain leather",  remains a marketing phrase that implies quality in leather furniture.  It's unfortunate, and raises suspicions about things like dyes, particularly because we use dyes to manufacture everything from soaps, cosmetics and even the foods we eat and drink. In the printing industry, the term "flexographic printing" replaced the old term "aniline printing" in the 1950's for the method used to print color on foil. The printing industry wanted to avoid the nasty implications in the process from the term aniline. I wish we would do the same with the term "aniline" wood stain.

   Yet the term aniline has stuck in the synthetic dye world, and most dyes used in woodworking are not a true aniline dye, meaning, aniline or one of it's derivatives are used in the synthesis of the dyestuff. However, even when aniline may be used (and this is the most important point to remember), NO FREE ANILINE IS TYPICALLY PRESENT IN THE FINAL DYESTUFF. Aniline and it's derivatives are called intermediates, meaning they are products that are used as parent reactants to get something else. By the same token, there is no bleach in bleached flour, and no methylene chloride in decaffeinated coffee. One of the biggest uses for aniline (and it's derivatives) is the manufacture of pharmaceuticals. (that nitrogen group at the top of the ring is very useful).

   However, when it is used to make a particular dye, and because aniline is a carcinogen, the levels that may remain in the final product are required reporting for a MSDS sheet under "Hazardous Ingredients" if it's greater than  .1% or 100 parts per million. So if a particular dye contains free aniline (above 100 ppm) in it, the MSDS sheet should point it out, because the manufacturer is required by law to list it.

   In all the years I've looked at raw materials for wood stains, I've only run across one that listed free aniline as a hazardous component.  It's for that reason that Homestead has never referred to our wood stains as "aniline" dyes.

   Jeff Jewitt

   
   

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   Edited 3/31/2002 11:38:45 AM ET by Jeff

1. 
   Biscardi | Mar 31, 2002 08:35pm | #4

   Mr. Jewitt,

   Thank you for your excellent reply.

   Frank Biscardi