Conservation (8): Conservation of modern collections

It is often assumed that modern collections, such as LHSA's HIV/AIDS material, do not need conservation treatment. However, this material is still vulnerable to deterioration because of its inherent qualities or inappropriate storage methods upon accession. Often, modern collections in archives consist of unstable or low-quality materials, as they were not designed to last but sewere intended for practical and temporary use.

For example, modern paper made from low-quality materials may exhibit greater deterioration than an older paper object made with high-quality rag paper. Plastics formed 20 years ago may already be fading or becoming brittle, and modern materials such as VHS and audio tapes could be unreadable after just a few decades.

Problems can also arise with mixed media collections regarding how to store these items together in their original form without losing their meaning, while still adhering to conservation standards. Ethical issues also emerge, such as which items to retain and which can be disposed of. Questions about conserving modern materials will only grow as more modern ones are produced daily, making this a new and fascinating area.

Example of unsuitable housing of collection items upon accession.

Conservation of modern paper

Deterioration of modern paper

Often paper made in the past 50 years shows greater deterioration than papers made 500 years ago. For example, this newspaper page (right) found in the HIV/AIDS collection has discoloured and become brittle.

Paper deterioration can be caused by both internal and external factors.

Internal causes of paper deterioration

The raw materials and the manufacturing process of paper can cause degradation. 

Raw materials

In Europe, early papers were made from cotton, linen and hemp rags which were relatively stable and generally made good quality papers. However, as the demand for paper grew, papermakers began to use different materials and methods which resulted in lower quality sheets. In the 1840s, a method was developed for using ground wood pulp in the paper making process. This type of pulp contains lignin which is acidic and darkens on exposure to light.

The use of new materials, such as recycled fibres, optical brighteners and colourants and new manufacturing processes from the 1980s onwards has increased the types of paper available. However these processes and material all have an effect of the longevity of the paper and a paper conservator must be aware of the methods of production to successfully treat objects made from modern paper.

A newspaper that has discoloured over time, especially along the edges and folded areas.

Manufacturing process

Early papermaking was all carried out by hand, which resulted in a good quality strong sheet. However, it was a long and laborious process and many sought to mechanise the manufacturing procedure to increase production.

The first papermaking machine was invented in 1798 by Nicholas-Louis Robert. This mechanical pulping and formation resulted in shorter fibres and also unintentionally introduced metallic particles into the paper resulting in a weaker sheet.

Chemical pulping was introduced in 1854 by Hugh Burgers and Charles Watt. Chemical pulping removes lignin and does not cut up the fibres as much as mechanical pulping, resulting in a stronger paper.

From the mid-1970s thermomechanical pulping was widely used. This method uses heat and mechanical pulping to soften the wood chips used in paper making. Today, the sulphate process is most commonly used to produce paper. This is a chemical procedure in which wood chips are treated with sulphurous acid under high pressure to produce cellulose and extract lignin.

Alum rosin sizing was introduced in the early 18th century in an attempt to strengthen the paper; however, this sizing caused further acid to form within the paper. Wood pulp paper from before the 1980s also tends to be acidic due to the alum-rosin sizing used. The development of synthetic sizing in the 1980s enabled the production of paper with a neutral to slightly alkaline ph. This, combined with a calcium carbonate filler, acting as an alkaline reserve to prevent acid contamination from the environment, resulted in paper with better ageing characteristics than modern papers from the early 20th century.  

This resource by the Robert C. Williams Museum of Papermaking provides a good overview of the history of papermaking around the world: History of Papermaking Around the World

External causes of paper deterioration

Environmental conditions

Temperature: high temperatures increase chemical reactions. An increase of 10 degrees C doubles the reaction rate. Therefore, a cooler environment is preferred for paper collections.

Humidity: moisture in the air can also accelerate chemical reactions. High levels of humidity can aid mould growth and encourage pests. Equally, low levels can cause desiccation of the object and result in increased brittleness.

Fluctuation of these conditions causes the material to expand and contract. Over a long period of time, this can weaken the physical bonds within the paper and cause a loss of strength.

Pollutants

Gaseous pollutants can originate externally from industrial and vehicle fumes, or internally from common materials such as paint, plastics, cleaning supplies, and photocopiers. These pollutants, especially when combined with a humid atmosphere, can initiate chemical reactions that can result in paper degradation.

Light

The absorption of energy from light can trigger chemical reactions that degrade paper. UV light is particularly damaging as it has more energy than other longer wavelengths of light. Light can cause the lignin in paper to darken and cause inks and dyes to fade. Other forms of light such as direct sunlight and infra-red bulbs can also produce heat which again causes paper to degrade.

Handling and storage

In the HIV/AIDS collection, the majority of the damage to the paper documents is due to poor handling and storage during use, prior to accession. They were often used in offices and, as such, not handled with great care as they were just seen as ephemeral documents.

Paperclips and staples

Frequently, metallic paper clips or staples are used to hold loose sheets together; however, these can rust over time and cause planar distortion of the paper. These damaged areas now represent an area of weakness, which will be more susceptible to damage over time.

Creasing

Due to inappropriate storage and careless handling, papers can easily become creased. These creases weaken the paper fibres and may be more likely to tear in the future. This is often caused by inappropriate storage. For example, documents placed in a ring binder may exhibit tearing around the hole punches.

Tears

This is often caused by inappropriate storage. For example, documents placed in a ring binder may exhibit tearing around the punched holes.

 

Surface Dirt

Although it may seem innocuous, surface dirt can absorb pollutants from the atmosphere. These can then migrate into paper and increase the acidity of the paper. Surface dirt can also provide a food source for pests and encourage mould growth. Without appropriate storage, dirt can accumulate on the paper surface and result in paper degradation.

Conservation of modern paper

Surface Dirt 

Surface dirt has been removed using a chemical sponge. This method was chosen as it is quick and easy to prepare. It can also be used to target specific areas and is very effective at removing surface dirt

Removal of metal fasteners

In the HIV/AIDS collection, metallic fasteners such as paper clips and staples are frequently used to hold together loose sheets of paper. These items are all being removed to avoid the transfer of rust from the metallic fastener to the paper. Care must be taken to avoid the tearing of the paper during removal. 

Once these metallic fasteners have been removed, the nature of the object has been slightly changed and it may not be obvious that these items were previously held together. Therefore, simple paper tabs have been created to hold items that have had their metallic fasteners removed together. The number of metallic fasteners that have been removed has also been recorded so that the original appearance of the items can be recreated if necessary.

Creasing

Creasing has been reduced by gently rubbing the creased area with a bone folder over a piece of Bondina™. In some cases of extreme creasing, the paper has been carefully folded back on itself to help the fold lay flat. In most cases, the papers have been laid flat in the archival folders so that over time they will lay flat due to the weight of other paper items on top of them. In cases of extreme cockling, paper items have been placed in a press between layer of Bondina™ and blotter to reduce planar distortion.

Tear Repair

Tears have been repaired using Japanese paper and wheat starch paste.

Rehousing

All paper items are being rehoused into more suitable enclosures to provide better protection from mechanical damage and to avoid migration of acids from non archival storage methods.

Due to the size of the collection, it is not feasible to house each sheet individually. Instead, loose papers at a maximum depth of 2 cm are placed in triptych folders. These folders are then placed in acid free clam shell boxes.