Technical pens are commonly used by designers, drafters and architects and are most valued for their extremely reliable line quality. The term 'technical pens' also includes a range of mechanical pencils which are valued for providing a reliable, consistent drawing experience.
Unlike other forms of drawing tools, technical pens are specifically designed to give the user a predictable and consistent line width regardless of pressure, making them more convenient than disposable drawing pens. Technical pens usually display their line width on the barrel that is extremely accurate compared to disposable drawing pens – which only contain an estimated line width that can broaden, depending on the amount of pressure applied to the instrument. Another added benefit of using technical pens rather than disposable drawing pens, are their sustainable qualities – for example, many technical pens are refillable and if cared for properly, will last many, many years.
The Online Pen Company: Technical Pens
A technical pen is a specialised writing instrument used by an engineer, architect, or drafter to make lines of constant width for architectural, engineering, or technical drawings. They often use either a refillable ink reservoir (Isograph version) or a replaceable ink cartridge for ease.
Technical Pens: A History
Early technical pens consisted of a small pair of calipers with one flat and one bowed leg, holding the ink between them - by adjusting the gap between the two legs, the width of the line drawn by the pen could be adjusted.
When kept at a constant angle to the paper, technical pens were often used for ruling lines, but not for cursive handwriting, nor for off-hand flourishes. The first technical pen, Graphos, was introduced in 1934 and miniaturized the caliper principle, making the points easily interchangeable. Soon after Sheaffer produced an expensive drafting set which included such pens for use on linen prints. These drafting sets were often presented to a draftsperson upon completing their 'time served', marking the end of their apprenticeship.
A full set of technical pens would have the following nib sizes - 0.13, 0.18, 0.25, 0.35, 0.5, 0.7, 1.0, 1.4, and 2.0mm - all of which correspond to the line widths as defined in ISO (International Organization for Standardization) 128. However, the ISO called for there to be four standard pen widths and set a colour code for each: 0.25 (white), 0.35 (yellow), 0.5 (brown), 0.7 (blue). Instead, these nib sizes produced lines that related to various text character heights and ISO official paper sizes.
The main drafting sets of four nibs came in two different kinds, gold and silver. The Silver kind was more for rough tracing paper, and the Gold for plastic film like velograph or durables.
Years after their initial launch, drawing boards changed and so did technical pens as a result. Instead, a hard (not spongy) surface was required to be able use a drawing board, so a plastic film was used and the static attraction between plastic cursors, T-squares, and set-squares meant that as one lifted the edge from the film, the ink would blot.
In the end the solution was to stick down a plastic sheet called an Osalid that attracted the film more strongly than the drafting instruments did. The tracing paper or velograph sheet could then be placed on the Osalid sheet whilst stuck onto the drawing board, brushing the air away. Brushing instantly charged the surface, and the film would then be taped taut, but still released at the end of each working day to allow for temperature expansions and contractions.