The ink 4001 in blue-black can be categorized as relatively lightfast. It is an iron gall ink, which means that it is far more permanent than, for example, the 4001 in Royal Blue or Brilliant Black.

Thanks to the special ingredients in the formula, it can be used in both piston and cartridge fountain pens. Over time, the color of the ink changes from blue-black to gray, though the ink will always remain visible.

The flow of ink and width of the nib determine the thickness of the stroke made on the paper. The absorbing capacity of the paper also determines how much ink can be applied. One factor that also plays a very decisive role is the amount of time that the ink has been exposed to the light for.

This ink is not document proof. We recommend Fount India to all customers seeking an ink that is even more permanent than our 4001 ink Blue black.