How To Preserve Blueprints

How do you preserve blueprints? Blueprints, otherwise known as cyanotypes, can pose specialized concerns and challenges when it comes to handling and storage. Many times, due to the processes and materials used to create them, blueprints can become acidic and brittle. The method of creating blueprints was invented in 1842. This method became a popular way to reproduce building plans for architectural firms. Do you have fragile blueprints that require protection? Are you concerned about storing them properly?

The following are guidelines for storing and handling your blueprints or cyanotypes:

  • House them singly in folders made of unbuffered alpha cellulose.
  • Do not use glassine or wood pulp housing materials.
  • Blueprints will often fade if housed in an alkaline environment. Signs of image deterioration include tonal shifts from blue to yellow or brown, with the image progressively turning white over time.
  • Do not roll blueprints. They are so prone to embrittlement and fragility, storing cyanotypes rolled will increase the chances of damage occurring.
  • Do not place blueprints in plastic or polyester sleeves. Due to their acidic nature, the blueprints offgas. If placed in a sleeve of any kind, the acidic degradation products will not be allowed to dissipate into the surrounding atmosphere, and will remain trapped in a microenvironment with the blueprint. This, in turn, will accelerate the aging and decomposition of the cyanotype.
  • Minimize exposure to light. Store your blueprints in a cool, dark environment, with a relative humidity between 30-50%.

Sources for storage supplies include:
Gaylord Archival:
University Products:

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