Rotring Rapidograph Technical Pens

The Rotring Rapidograph Technical Pen is a development from the earlier Isograph series and represents the furthest advancement made in this type of drawing instrument.
Rapidograph Technical Pen use a disposable ink cartridge and will perform only with compatible Rotring 591017 Ink Cartridges.
The crucial difference between the Rapidograph and other technical pens lies the breathing system. Earlier versions always had the breathing system, where air replaces the ink, incorporated in to the nib of the pen.
When a technical pen is in use the heat from the hand causes the ink inside to expand and this expansion has to be compensated or ink would be forced out of the tip on to the drawing.
Instead it curls down the spiral section known as the helix when expanding and is drawn back up on contracting when it cools. This action coats the helix with ink that requires regular cleaning. As many users neglected this process of cleaning on earlier models Rotring designed the helix to be incorporated in to the replaceable ink cartridge and left the nib smooth. The result is a more efficient ink flow and cleaner operation.
The Rapidograph series conforms to ISO Standards of line width and is compatible with lettering stencils of this standard.
As with all technical pens they were designed to perform a highly specialised function and an understanding of this is useful should you wish to use one for another style of drawing. Full details follow.

Then: Rotring Rapidograph Technical Pens are a development that met the industry requirements of the time. These requirements, in brief, were to produce drawings in standardised line widths and lettering heights that were in the most opaque black lines possible on translucent papers such as trace and film.
This all related to the available technology of reproducing copies of the drawings using the Diazo method. Briefly this method used ultraviolet light to expose a sensitised paper that was laid underneath the drawing. This exposure removed the sensitised coating except where the ink lines on the drawing “shadowed” it. The paper was then separated from the drawing and “developed” by exposure to ammonia fumes – all this taking place in a plan printing machine.
The blacker and more opaque the lines the quicker you could print your drawing and often very large quantities were required so it was essential to maximise the efficiency of the process.

Now: The technical pen remains the means for laying down the blackest fine line possible and this has many applications outside the original intention of the design. While many are still in use for traditional manual drafting there is a following amongst designers and sketchers who appreciate the precision of this very specialised pen.
It should be understood that the Isograph Pen, as with all technical pens, was only designed for use on tracing paper and film. Other types of media do not necessarily have a surface suitable for the fine tip of these pens and if fibres of such media get picked up by the pen point they will inevitably clog it up.
To achieve the opacity demanded the inks are made from a formulation of glue, soot and shellac. These are suspension type inks where particles of the black pigment (soot) is suspended in liquid.
This requires diligent care of the pen so as to avoid clogging. Regular cleaning of the helix to maintain air intake is wise and keeping the ink reservoir close to full helps prevent flooding.
Of all operating tips the best is as follows. Always cap the pen immediately once you stop drawing with it. If not capped the ink will quickly dry in the tip of the pen. If you cap it after this ink has been allowed to dry this dried contaminant can be pushed up in to the point making starting the pen next time difficult. If it becomes firmly blocked then shaking the pen to get the ink flowing can actually damage the internals of the nib. Always cap the pen when it is still working – draw a quick line – then screw the cap on firmly. This will greatly improve the odds of it starting again next time you go to use it.

Other Terms for these Products

rapidograph pens, rotring pens, rotring technical pens, rot ring pens, draft pens, drafting pens, technical pens, technical drawing pens, draftsman pens, ink pens, drawing pens, refillable pens, plan pens, tracing pens, tracing paper pens, draft pens.