I used to thin the dye with denatured alcohol, but found the pieces would often crack, as the alcohol has a high water content. I now switched to thinning the dyes with acetone.
Changing or enhancing the color of wood while letting its grain show through has been a favorite finishing technique for centuries. Today we often accomplish this with pigmented stains. But before the 1850s, most wood coloring was done with natural dyes available then, extracted from roots, berries, bark, and even insects, sea snails,yielded beautiful, clear colors. But they weren’t lightfast, so the dyed wood faded or changed color over time. In the 1850s, a British chemist accidentally produced a strong purple dye while working with aniline, a clear, oily, poisonous liquid. Subsequently, scientists synthesized other dye colors. These synthetic dyes delivered the same sparkling colors as the natural ones and were s’more lightfast to boot. They were cheaper, too. Derived mainly from coal tar, synthetic dyes in general came to be known as aniline dyes, and a new chemical dyemaking industry sprang up around them. Metal complex dyes are the new generation. They are more colorfast than the old aniline dyes.
The dyes are fine powders. Metal complex dyes offer an attractive finishing choice today. Pigmented stains, which some people characterize as thinned paints, may mask the wood’s figure and can lend wood a muddy look. But transparent dye colors, even dark ones, can bring out the grain and add depth.