EACH - RAPIDOGRAPH PEN 4

Size 4, 1.20mm

A technical pen is a writing instrument designed to produce an extremely uniform, dense line. It must meter ink so that the line width remains the same from start to finish, and produces a line dense enough for photographic reproduction. The pen does this using the principal of capillary action. The ink flows down a tube and around a wire that is inside the tube. The wire also breaks the surface tension when the point touches the drawing surface. A technical pen is a sensitive instrument that requires care and must be used with the right ink (see ink products later in this section). It is also recommended that the point and wire not be disassemble during cleaning.

KOH-I-NOOR RAPIDOGRAPH
The Koh-I-Noor Rapidograph® features an extra smooth feel on the drawing surface. The patented dry double seal cap system seals the entire nib and tube orifice This helps eliminate drying out. 10 different line widths are available that are marked in standard and metric sizes. Nine of these sizes are in widths that conform to the International Standards Organization (ISO). Based on the square root of 2, these sizes facilitate the half scale blow back technique, common in microfilm practice.