Dr. Ph. Martin's Synchromatic Transparent Watercolors are easy to handle and offer ultimate transparency. They're ideal for use in airbrushes and technical pens due to their no clogging formula. They're designed specifically for work that requires more transparency, such as retouching, hand coloring for photographic papers, and films. Like all aniline dye base colors, they are fugitive when exposed to direct sunlight over time.