What is the difference between Radiant Concentrated and Synchromatic Transparent?
Radiant Concentrated is a highly concentrated liquid dye. It requires shaking before use. Radiant has a pigmentation in it that makes it hazy on large areas of film (translucent). They are much brighter colors than Synchromatic and there are 12 fluorescent colors in the 56 color Radiant Concentrated line.
The Synchromatic is completely transparent, does not require shaking before use. It is completely transparent on film and has been recommended by Kodak for photographic papers and film retouching and hand coloring. There are 38 colors in the line. Only three colors are fluorescent: #24, #28, and #37. Synchromatic is a step down in brilliance from Radiant Concentrated. Most colors in both lines can be intermixed.
Radiant Concentrated can be made permanent for dying silk, cotton, batik, or tie dye by using additives such as: salt and vinegar, alum, or soda ash (sodium carbonate). Make a test piece first to test the wash fastness of the dye on fabric.

Are Spectralite Liquid Acrylics or Hydrus Fine Art Watercolor an ink or a dye?
Spectralite and Hydrus are both made with Fine Art pigments. They are lightfast fine artist pigments—the same type of pigments used in tube watercolor and tube or paste acrylic. There is no dye in these products. Many artists mistake the word "ink" as a type of colorant. It is a generic term for a liquid color which can be either a dye or a pigment.

Are Spectralite Liquid Acrylics or Hydrus Fine Art Watercolor Lightfast?
Yes, all of the colors in both lines are lightfast pigments. Our other lightfast lines are Iridescent and Bombay.

What type of colorants are used in artist colors?
There are two basic types of colorants, pigments and dyes. However, there are many types of dyes and only a few type of pigments. Dyes can be classified as natural or synthetic. Within the class of synthetic dyes there are many types: i.e. acid, basic, mordant, fiber reactive, oil soluble,  or water soluble. In the pigments there are the organic and inorganic, natural and synthetic. Do not mistake the word organic when applied to pigments to mean "natural." It has a different meaning in chemistry.

The History of Dr. Ph. Martin's & Salis International, Inc.
While Dr. Ph. Martin's Radiant Concentrated Water Colors were originally manufactured in 1934 by B. Aronstein & Co. in Flushing, New York, Salis International, Inc. has been the sole manufacturer of Dr. Ph. Martin's artist products for the better part of the last century. 
In 1936 a 16-year old Ben Salis started work for the company. He was paid $1.00 a week. Ben became know as "Doctor Martin," as he invented many products and held several design patents. Ben became owner of the company. As it grew it developed a reputation as the best commercial art product company for liquid color worldwide. I joined my father in 1970 in partnership and become owner in 1980. My grandfather worked in the business for 20 years. My brother also worked in sales. This family business is now 82 years old. Dr. Ph. Martin's trade name was chosen by the original owner of the business in 1934. In the 1930's and earlier, products with the trade name of "Doctor" in the title were given instant respectability and flourished. Now there are only a handful of well known doctor products on the market.
Dedicated in memory of my father 1919 – 1996.

Larry Salis 
Salis International, Inc.