For my column in the current issue of Popular Woodworking Magazine, April, 2017 (#231), I wrote about how brands of water-soluble dye stains sold to the woodworking community differ. One of the differences is the degree to which they can be redissolved and lightened by wiping over with a wet cloth.
My point was that you can choose for the characteristics you want, and I included a picture that was supposed to show the differences. But one of the problems with print media is that subtle differences often don’t show up well, and they didn’t in this picture.
So I realized that with this blog I have a second chance in digital media, which I think shows the differences better.
In the article I discussed the three types of water-soluble dyes available: acid, metal complex and metal complex with the addition of an acrylic resin.
Metal complex dyes are available in liquid form as TransTint and Non-Grain-Raising (NGR) from Woodcraft, Rockler, Klingspor and paint stores that cater to the professional trade. They are also often available in powder form from these suppliers and from Lockwood.
You can spray any finish over each of these dyes without problems. But brushing water-based finish directly over an acid dye will move the color around and may leave some darker lines in metal complex dyes. You should use another finish as a sealer coat, or spray a first coat of water-based finish, maybe with an aerosol if you don’t have a spray gun.