Dr. Ph. Martins Tech drawing ink contains fine artists pigments to ensure transparent, lightfast, archival results. Designed specifically for use with technical pens, calligraphy pens, and drawing pens. It also works well with brushes and airbrushes. Tech drawing ink is acid-free and waterproof. Ideal for design and illustration. Each Set includes 12 different colors in 1.0 oz (30 ml) glass bottles with droppers and a custom mixing palette. Set colors: 2w daffodil, 3w orange, 4w scarlet, 5w rose, 6w rhodamine, 7w turquoise, 8w indigo, 9w april green, 10w spruce green, 11w olive green, 12w gold ochre, 13w antelope.