Historic cartographic document showing aging, discolouration, and handling wear typical in paper records
A historic cartographic document from the Leventhal Map Center showing characteristic aging: discolouration, foxing, and edge deterioration. Paper technical drawings follow similar deterioration patterns. Source: Wikimedia Commons / Norman B. Leventhal Map Center, CC BY.

Types of Technical Drawings in Home Collections

Canadian homeowners often retain technical documents related to their properties: architectural drawings from original construction, renovation permits with attached plans, plumbing and electrical schematics, and in some cases older survey drawings on linen or film. These documents vary substantially in the medium used to produce them, which affects both their vulnerability to damage and the appropriate storage approach.

Diazo and Blueprint Prints

Documents produced by the diazo (whiteprint) process — the blue-and-white or black-and-white prints commonly called blueprints — are light-sensitive. Continued exposure to ultraviolet radiation causes the lines to fade irreversibly. This process is slow under dim indoor lighting but can be rapid near windows with direct sun exposure. Diazo prints should be stored in opaque enclosures and never displayed in direct light.

The original "true blueprint" process, which produces white lines on blue background, is less common in documents from the 1970s onward, but both types share light sensitivity as a primary vulnerability.

Ink-on-Vellum Drawings

Architectural drawings from the mid-twentieth century were frequently produced in ink on translucent vellum or drafting paper. Vellum is cellulose-based and prone to brittleness as it ages, particularly at fold lines. Vellum drawings should not be folded; rolling or flat storage is necessary.

Polyester Film Drawings

Drawings on polyester film (Mylar) are dimensionally stable and chemically inert — they do not expand and contract with humidity changes the way paper does, and they do not produce acids as they age. They are, however, prone to surface scratching and to losing pencil or graphite marks if the surface is abraded. Polyester film originals should be stored in smooth, non-abrasive enclosures.

Photocopied and Printed Reproductions

Laser-printed and photocopied technical documents are among the more stable media for long-term retention. Toner-based images are chemically stable under normal conditions. The main risk is from the paper substrate, which may be acidic, rather than from the image layer itself.

Size Considerations

Technical drawings often exceed standard filing cabinet dimensions. Common Canadian construction drawing formats include:

  • ANSI D (559 × 864 mm)
  • ANSI E (864 × 1118 mm)
  • Architectural D (610 × 914 mm)
  • Architectural E (914 × 1219 mm)

Standard letter-size filing is insufficient for most of these. Flat file cabinets that accommodate A0 or E-size drawings are available but require significant floor space. For homeowners with a small number of large drawings, custom flat storage using archival boxes may be more practical.

Flat Storage for Large Drawings

Drawings that can be stored flat should be. The practical challenge is finding or constructing housing that accommodates oversize sheets without folding. Options include:

Oversized Archival Boxes

Archival supply companies offer flat boxes in large formats. These can be purchased with acid-free board as a base and placed on shelving. Interleave drawings with acid-free tissue, and do not stack more than 10–15 sheets in a single box, as weight from upper sheets can cause micro-deformation of lower ones.

Map Cases Under Beds or Tables

A shallow case on casters that slides under a bed or worktable provides flat storage without requiring dedicated floor space. The case should be sealed to prevent dust accumulation. Lining with acid-free board creates a stable internal environment.

Rolled Storage for Oversized Drawings

When flat storage is not available, rolling in archival tubes is the next best option. Specific requirements for technical drawings:

  • Roll prints with the image side outward (facing away from the tube centre) to reduce cracking of media layers.
  • Use a tube diameter of at least 12–15 cm for large drawings; a tighter curve stresses heavy paper and vellum.
  • Wrap drawings individually in acid-free tissue before rolling. Do not roll multiple drawings together in direct contact.
  • Label tubes with their contents, including drawing number, date, and subject, to avoid unnecessary unrolling for identification.
  • Store tubes on horizontal padded supports. A simple shelf lined with foam pipe insulation holds tubes securely without point pressure.
Blueprint light sensitivity: Even when stored in tubes or boxes, diazo prints can fade if the container is left open near windows for extended periods. Store in opaque tubes or wrap in opaque tissue before rolling and inserting in any container.

Environmental Control

Technical drawings, like other paper documents, benefit from stable temperature and humidity. Diazo prints have an additional requirement: they should be stored away from alkaline materials because alkalinity can cause the diazo image to shift or fade. This means that while acid-free enclosures are standard for most documents, buffered alkaline papers should not be in contact with diazo prints. Use unbuffered acid-free tissue with these documents specifically.

For polyester film drawings, environmental stability is less critical for the drawing itself, but adhesive labels or annotations on the film surface may fail in high humidity or high temperature.

Handling Practices

Each time a technical drawing is unrolled or removed from flat storage for consultation, it is exposed to handling risk. Practices that reduce damage:

  • Work on a clean, dry, smooth surface. Hard tables with no clutter prevent accidental tearing from edge contact.
  • Use clean cotton gloves when handling older blueprints or vellum drawings. Oils from hands transfer to paper and can create permanent staining over time.
  • Unroll slowly, placing weights on corners to flatten without forcing. Do not press hard on fold lines to flatten them — this can crack media layers.
  • Photograph or scan before returning to storage if handling revealed deterioration, so a reference copy exists if the document continues to degrade.

Prioritising Which Documents to Preserve

Not all technical drawings in a home collection have equal significance. Original permitted architectural drawings, drawings showing foundation or structural details, and drawings predating significant renovations are generally higher priority than reproduced general-arrangement plans or copies of standard manufacturer specifications. Resources spent on enclosures and environmental control are most justified for documents that cannot be easily replaced from another source.

Useful References

Last updated: May 22, 2026