Sakura Souffle pens feature a unique 3-D ink that leaves a pastel-like raised line you can see and feel! They can write on regular paper as well as non-porous surfaces like plastic, glass, and metal. They can be used on white or colored paper, and their colors stand out particularly well on dark surfaces. The ink is waterproof on most surfaces, water-based, odorless, and AP certified non-toxic.
For best effect, write slowly to allow a thick line of ink to form and allow the ink to dry completely, which can take up to 10 minutes on most surfaces. Because the ink is thick and slow to dry, it is not ideal for extended writing. The raised effect works best on non-porous, clean, smooth surfaces and can be crushed down by pressing on it.