Everything about this pen, from its solid construction to its carefully-formulated ink, ensures a wonderful writing experience. The sturdy tip does not bend or break, even with heavy-handed use. The pigment-based ink flows smoothly and is waterproof, fade-resistant, and feather-resistant. Much of that is due to special viscous properties of the ink. The ink is viscous while in the barrel, but as it passes through the pen tip during writing, the viscosity drops. This results in smooth ink flow. Immediately after it hits the paper, the ink returns to its viscous state, which prevents feathering. You are left with beautiful clean lines that you can enjoy for a long time! Uni-ball Signo gel ink pens are known for their smooth writing and exceptional ink quality. The sturdy tip does not bend or break, even with heavy-handed use. The pigment-based ink flows smoothly and is waterproof, fade-resistant, and feather-resistant.