Winsor & Newton's professional quality ink was especially developed for writing and calligraphy. The range consists of 18 vibrant colors which are lightfast, intermixable, and non clogging for improved flow. That bright colors easily blend and dilute and are suitable for application with a pen, brush and airbrush. Single pigments have been used wherever possible and all colors have a permanence rating of AA or A. Available in 30ml bottles. Non-waterproof.