Overview
ISO 6428:1982 consolidates and expands the rules of ISO 128, ISO 3098 and ISO 5457 to define how original technical drawings and associated drawing-office documents should be executed for reliable microcopying. The standard's objective is practical: produce high-quality microforms that yield legible enlargements and that can also be reproduced by other reprographic systems.
Key benefits: improved archival microforms, predictable enlargement quality, and cross-reproducibility by different reprographic processes.
Key Topics
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Materials and sheets
- Blanks or pre-printed sheets may be transparent, translucent or opaque, but the face used for drafting should be matt to reduce reflection and maximize contrast.
- Polyester drafting film is recommended for dimensional stability and durability (document notes a minimum film thickness of about 76 μm).
- Sheet sizes should comply with ISO 5457.
- Edge binding is not recommended unless unshrinkable adhesive tape is used. Adhesive overlays require care due to dust accumulation and ageing.
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Lines, density and spacing
- All lines (representations, symbols, lettering and revision marks) should have a matt finish and consistent density. A recommended minimum contrast value is 0.7 relative to the sheet background.
- Parallel-line spacing should be at least twice the thickness of the heaviest line, with an absolute minimum spacing of 0.7 mm.
- For AO and A1 originals that may be enlarged, a minimum line thickness of 0.35 mm is recommended.
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Lettering and text
- Lettering shall comply with ISO 3098/1. Use of capital letters improves clarity for character images on microforms.
- When mechanical lettering (typewriters, plotters) is used, matching the density of other lines is advised. Minimum character heights are recommended in the standard for different sheet sizes.
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Areas, pencil work and erasure
- Avoid large solid black areas; use hatching or dotting if necessary.
- Pencil drawings are not preferred but may be used if polymer leads and matt, even-density instruments are selected. Fixatives can reduce smudging but may affect future erasure.
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Storage and handling
- Originals should be stored flat or suspended and not folded. Documents may be rolled for transit only, and then wrapped around a tube (typically large-diameter) and unwrapped promptly.
Applications
- Archival microfilming of technical drawings and associated office documents
- Preparing reproductions for engineering offices, libraries and record centers
- Establishing consistent reprographic quality across plotting, typewritten and hand-drawn originals
Related Standards
- ISO 128 - Technical drawings: General principles of presentation
- ISO 3098 - Technical drawings: Lettering
- ISO 5457 - Technical drawings: Sizes and layout of drawing sheets
- ISO 3272 series - Microfilming procedures and quality criteria
Adopting ISO 6428:1982 practices ensures documents are future-proofed for microcopying and other reprographic workflows, improving legibility, reproducibility and long-term archival quality.
