The Jakar Ruling Pen is a precision drawing instrument with a long history in technical drawing, illustration, and calligraphy. Two adjustable metal blades hold ink between them by capillary action, and the gap between them — and therefore the line width — is controlled by a simple screw adjustment. Dip the tip into ink, adjust the screw to your desired width, and draw against a ruler or straight edge for clean, consistent lines of any width from hairline to several millimetres.
Beyond technical drawing, ruling pens are popular with artists for applying masking fluid in precise lines before watercolour washes, for ink line work, and for calligraphic mark-making that produces variable line widths through changes in angle and pressure. A tool with genuine versatility in the right hands.
- 140mm ruling pen
- Screw-adjustable double blade tip — variable line width
- Ink held between blades by capillary action
- Black plastic handle
- Supplied in a transparent plastic hanging wallet
- Suitable for ink, masking fluid, and liquid media
- Brand: Jakar
- SKU: 1191
Frequently Asked Questions
How does a ruling pen work?
The two metal blades at the tip of the pen hold ink between them by capillary action — surface tension keeps a reservoir of liquid between the blades. The screw controls how far apart the blades are held, which determines how wide a line the pen draws. Dip the tip into ink (do not overfill), adjust the screw, hold the pen upright, and draw against a ruler or straight edge for a consistent line.
What can I use a ruling pen for?
Ruling pens are used for technical drawing and drafting, precise ink line work in illustration, applying masking fluid in straight lines before watercolour washes, and calligraphic mark-making. They require some practice to use well but produce results that other pens cannot match for precision and variable width.
What inks and media work with a ruling pen?
Drawing inks, Indian ink, and masking fluid all work well. The pen should be cleaned thoroughly after use — dried ink between the blades is difficult to remove and will affect performance. Rinse with water (for water-based media) or the appropriate solvent immediately after use.
Is this a general writing tool?
No — a ruling pen needs to be held quite upright and dipped frequently, and works best against a ruler or straight edge. It is a specialist drawing tool rather than a writing instrument.
