Overview
ISO 9957-1:1992 specifies requirements and test conditions for water-based India ink intended for use on natural tracing paper. The part focuses on reproducibility and archival performance of drawn lines when used with tubular technical pens and conventional reproduction techniques (blueprint, microfilming, photography, electrostatics). The standard defines test atmosphere, sample preparation, and objective methods to measure line quality and durability.
Key Topics
- Test environment: Standard test atmosphere 23/50 (humidity/temperature) is required for conditioning and testing.
- Line width: Lines are drawn using a tubular technical pen in a line-drawing device. The drawing angle (87°), pen loads (e.g., 0.1 N for small-width pens), drawing speeds and measurement method are specified. Line width is the arithmetic mean of 20 measurements with 0.01 mm accuracy.
- Optical density: Measured with calibrated densitometers for transmission and reflection. An optical density of about 1.0 is noted as providing adequate contrast for reproduction.
- Drying time: A practical finger-smear test is used (wipe after 10 s under specified conditions); absence of smearing indicates drying.
- Adhesion: After a short drying interval (5 min), ordinary adhesive tape is applied and removed; no visual loss of optical density indicates acceptable adhesion. A pencil/eraser scratch test is also specified.
- Erasability: A 30 mm section of line is erased after drying and a new line is drawn across the erased area. The redraw must show no feathering and remain within permissible width deviations.
- Resistance to water: A test uses drops of deionized water applied after drying (15 min) to check for ink spreading.
- Fade resistance: Exposed versus unexposed comparisons after filtered Xenon lamp exposure (energy specified in the standard) are used to detect any recognizable difference in optical density.
Applications
- Ensures archival quality for technical drawings produced with water-based India inks on tracing paper.
- Guides manufacturers of inks and tubular technical pens to meet reproducible line performance for microfilming, scanning and traditional reprographic workflows.
- Useful for quality control in engineering, architectural and archival reproduction processes where stability, legibility and reproducibility are required.
Related Standards
ISO 9957 is a multipart series under the general title "Fluid draughting media". Relevant cross-references include:
- ISO 9961 - Natural tracing paper (substrate specified for tests)
- ISO 9175-1 / ISO 9175-2 - Tubular tips and performance for technical pens
- ISO 5-2 / ISO 5-4 - Density measurement geometry for transmission and reflection
This part of ISO 9957 provides practical, testable criteria to evaluate water-based India ink performance and compatibility with drawing media and pen hardware.