Architectural Papers (Blueprint)

Risks of Handling/Use

Generally, handling and use heightens the risk of damage to your materials, be it through neglectful handling (e.g. touching photo emulsion with bare hands) or irresponsible operation of access equipment. This is a risk posed by patrons and staff alike, intentional or not.

Handling and Collections Care

One of the easiest areas to implement protections for collections is through careful handling and sensible collections care. The unfettered use and handling of materials heightens the general risk of damage--be it through neglectful handling (e.g. touching photo emulsion with bare hands) or irresponsible operation of access equipment. Whether intentional or not, this is a risk posed by patrons and staff alike.

Examples of neglect, mishandling, and mismanagement include:

Pressure-sensitive (such as "Scotch®" brand) tape to mend tears.
Permanent or volatile inks used to label documents (even the back side).
Folding materials to fit into a given box or enclosure.
Poor handling: Not washing and drying hands before handling fragile documents; or not using gloves when handling materials that could be damaged by contact with oils on the skin (for example: gloves must always be worn when handling metals).
Inadequate storage or exhibit environments, such as areas with excessive climate swings or the use of poor display mounts.
Inadequate packaging/padding for shipping
Lack of bibliographic control over holdings, which has led to the harmful and excessive use of unique or vulnerable items.

General Recommendations:

Use archival-quality folders, boxes, sleeves, and other enclosures to support and house materials of differing shapes and sizes. Avoid use of acidic containers such as brown paper bags and shipping or moving boxes.
Use only Photographic Activity Test (PAT)-compliant storage enclosure materials for valuable photographic materials.
Wear gloves (either cotton or nitrile) while handling archival photographic emulsion materials and museum objects.
Avoid wearing cotton gloves while handling particularly fragile or slippery items, since gloves can hamper tactile senses and lead to accidentally dropping and breaking objects.
Handle fragile materials as little as possible.
Use clean, dry hands with carefully trimmed nails to handle materials (even when wearing gloves).
Use both hands and ask for assistance when handling/moving oversized materials.
Remove jewelry and accessories, including anything hanging around the neck or clothes that may inadvertently come into contact with and damage materials, such as: necklaces, headphones, glasses hanging around the neck, nametags, scarves, rings, watches, bracelets, ties, loose sleeves, and belts. Avoid wearing loose clothing.
During transport, use enclosures, supports, book carts, and other equipment as appropriate to minimize the risk to materials. Use materials like foam and snake supports to ensure that items are supported and do not come in contact with other items or with the sides of carts during transport. Always ensure sufficient assistance while transporting items.
Only use pencils for direct labeling (e.g. on a photo verso) of paper, AV, and photographic materials or folders/enclosures. Never use or carry pens around items and materials.
Ensure that patrons know and understand guidelines on proper handling of all fragile materials.
Ensure that staff, volunteers, and patrons are adequately trained in handling collection materials.

Additional Copies

The use of additional copies for reference or display purposes is highly recommended, particularly if the item is an original or valuable. This provides broader access to the content while also protecting the original document from user wear and tear or environmental factors.

Recommendations for care of original object:

Ideally, originals should be used once to produce an access copy, facsimile, or surrogate;
Copies would then be put to use by the institution in place of the original, sustaining the wear and tear of patron use or prolonged exhibition.

To learn more about best practices for use and access, including resources for creating digital surrogates, see Use & Access in the User-Manual.

Orientation in Storage

Store flat. If space for flat storage is not available, it may be acceptable to store the prints rolled. Brittle or otherwise fragile prints should not be rolled. Prints that are strong and flexible enough to be rolled must have an interior support, which should be a neutral pH cardboard tube (over 3" diameter) wrapped in polyester or neutral paper. The rolled print may also be wrapped in the neutral paper or polyester, and they should be stored horizontally, not upright. Prints should not be folded; this will create fold lines that stress the paper fibers and cause it to tear. All storage materials should pass the Photographic Activity Test (PAT) as specified in ISO Standard 18916:2007.

Storage Container

Technical prints were generally not made with long-term stability in mind; most were created quickly and cheaply to serve an ephemeral, utilitarian purpose. Many of these prints will retain chemical residues from processing. These residual chemicals may off-gas or cause damage if placed in contact with other prints. Blueprints/cyanotypes should be stored in alkaline-free paper products in order to prevent fading of the blue pigment. Buffered paper should be avoided. Prints are usually large; they should be stored horizontally in flat files or rolled if flat storage is not possible. Enameled steel, stainless steel, or anodized aluminum flat files are preferred. Store different types of technical prints separately in order to prevent contact degradation. Folders cut to drawer size are recommended, with less than 12 prints to a folder and with interleaving sheets placed between them. Individual prints may be stored in polyester sleeves within folders in order to protect particularly fragile items or to separate formats from one another. Polyester sleeves also provide additional support during handling.

Labeling

If your item has any kind of labeling on the container, the item itself, or any related material, we highly recommend that you return to the Basic Info section and enter this information in the appropriate field(s).

Labeling on a container or on the item itself, if it is in fact correct, can offer important clues about its content. If you are replacing a container that holds labeling information, it is important to transfer this information to the new container or label. Be sure to copy down any titles, dates, or other data found on these items and save your notes. Container labels should be used with caution as they are frequently reused or easily switched by accident.

For sleeves and folders especially, remember that it's generally best to label with a no. 2 pencil. If ink must be used (i.e. on a plastic enclosure), use an archival pigment-ink pen (e.g. Micron).

Physical Damage

Regardless of its acidity and inherent vice, all paper is susceptible to tearing and other forms of mechanical damage. Water exposure can affect the structural integrity of paper, leading to desiccated or brittle paper, which is more easily torn and damaged through handling. If paper has been folded, creased areas will be especially vulnerable to tearing.

Unbound paper may be damaged by fasteners like paper clips, and they are especially at risk during removal of fasteners. Metal fasteners that are not stainless steel will eventually corrode, and plastic fasteners may cause warping. For information on the correct removal of fasteners, consult the NEDCC leaflet on the Removal of Damaging Fasteners from Historic Documents.

Impact of Damage on Visual Information

Blueprints are relatively stable and image permanent if kept in dark storage conditions and out of an alkaline pH environment. The integrity of the support paper is often the decisive factor in the long term preservation of blueprints.

When evaluating the impact of damage on visual information, look for mechanical damage as well as deterioration and decay that obscures or limits access to information. This could include yellowing and embrittlement, both types of damage especially symptomatic of newsprint and other wood pulp papers. Damage could also include fading, darkening, warping, cockling, blocking (especially of coated papers), tearing, mold, and insect infestation.

Mold / Pest Damage

Pests like insects and rodents tend to like paper and textile materials. High humidity (higher than 68% RH) promotes mold growth and insect infestation, both of which can cause permanent damage. When assessing the exposure of your collections to pests, it is necessary to look not just at the materials themselves and their containers, but also to look at the larger environment. Insects and rodents tend to leave droppings in areas they inhabit. Insects tend to leave behind a substance called frass, which is the undigested fibers from paper. If you see droppings and/or frass in the storage area, it is a strong sign that your materials are being exposed to pests. Small, irregular holes on paper-based enclosures are also a sign that pests have attacked your materials.

Some tips for reducing your materials' exposure to pests are to refrain from eating anywhere near your collections materials. Crumbs draw pests, so keep food far away from your collections. Another tip applying to both pests and mold is to be cautious about donated materials when you receive them. Pests and mold can hitch a ride into your facility on these materials, so having a good, clean staging area where you can inspect donated items for, among other things, pest and mold evidence can help you reduce your storage environments' exposure to both.

Support Type

Before the 1870s, architectural and technical drawing copies were produced by hand using translucent tracing paper or drafting cloth. Blueprinting was introduced to architectural and engineering professions in North America in the mid-1870s, and it quickly gained popularity. Many new photo-reproductive processes followed using a variety of light sensitive materials, paper and cloth supports, and processing methods. Many of the processes used to strike prints from drawings were also used in other commercial applications (e.g. office reprographics). These prints were produced by photo-reproductive and photomechanical methods.

A blueprint is a single-layer print comprised of a blue pigment embedded in uncoated paper or cloth fibers. The ground color is a brilliant "Prussian" blue with continuous tone. The paper fibers are clearly visible, and the texture of the paper or cloth will likely be rough. Surface finish is extremely matte with no surface gloss, due to the absence of a binder layer. Most blueprints are negatives, with white image/text lines on a dark blue background, but sometimes positive images were also created to allow for easier reading. These positive prints (dark blue lines on a light ground) were known as pellet prints. The verso (back) of either type of print will likely be white or off-white (or color of the support paper/cloth).

For more information, visit the supplementary profile for Architectural Drawing Reproduction Support in the Collection ID Guide.

Paper Decay

Paper is sensitive to light and water exposure, high humidity, and high heat. Exposure to light and/or heat will accelerate deterioration in the form of yellowing and sometimes embrittlement.

Acidic paper (pH below 7.0) commonly exhibits deteriorative traits. Colored media on the paper support will fade rapidly. Water exposure can ultimately lead to desiccated or brittle paper, making it more easily torn or damaged through handling. Fluctuating temperature and RH may result in warping or cockling of the paper surface. High humidity (higher than 68% RH) promotes mold growth and insect infestation, both of which can cause permanent damage.

Even pH neutral papers will become increasingly acidic over time. This is due to the fact that cellulose naturally generates acids as it ages. Papers, including book leaves, that are darker and more brittle along their edges than center demonstrate an absorption of airborne pollutants that have formed acids.

Soil and dust may become ground into paper fibers, permanently soiling or staining the paper surface. Foxing is a common form of paper deterioration, which manifests as reddish-brown spots or blotches that appear embedded in the paper surface. Foxing is caused by a number of factors, but it is commonly spurred along by high humidity.

Cloth Condition

Architectural reproductive prints are often found on drafting cloth supports, or prints on paper may be mounted on muslin cloth. Cloth supports may become limp due to the presence of residual and oftentimes acidic chemicals. Mechanical damage and deterioration may result in fraying.

Drafting cloth is among the most common supports found in 19th and early 20th century architectural and technical drawing collections. Introduced in the 1850s, this flexible, durable alternative to paper was used primarily by architects and engineers for process drawings, tracings, and reprographic prints (e.g. blueprints, diazotypes).

The fabric is typically cotton or linen, which is starched and calendered to create a smooth, glossy drawing surface. Over time, additional oil and plasticizer treatments improved translucency and water-resistance in drafting cloths. Prior to the 1880s, cloths had an off-white or natural color; after 1880, a bluish-white tint was common, due to a colorant used to increase transparency.

By the mid-20th century, drafting cloth fell out of favor after the emergence of synthetic (i.e. acetate and polyester) drafting film. Regardless of composition, some refer to all types of drafting cloth as drafting linen, or simply as "linen."

Ink/Media Deterioration

Blueprints are very sensitive to light, but they are otherwise quite stable if kept in dark, non-alkeline, storage. Faded blueprints may regain substantial image density when kept in dark storage.

Characteristics of ink and other media vary depending on their composition and method of formulation. As such, the stability of media has a long-term effect on its paper support, and vice versa. It should be assumed that all media has potential to fade under extreme light exposure and that ink will bleed or transfer if exposed to moisture.

For assistance evaluating symptoms of media deterioration, see Common Types of Media.