Caring for Works on Paper

Why works on paper need particular care

Caring for works on paper starts with understanding why they are more vulnerable than most other objects in a collection. Paper is thin, absorbent and made of fibres that respond quickly to light, moisture and the materials they touch. The media on it, from watercolour and ink to pastel, charcoal and coloured pencil, are often more sensitive still.

Several things follow. Light damage shows sooner on paper than on an oil painting and cannot be reversed. Changes in humidity make sheets expand and contract, which can leave them cockled. Acids from poor-quality mats, boards and papers migrate into the work over time and cause discoloration and brittleness. And friable media such as pastel and charcoal sit loosely on the surface, where a touch or static charge can smudge or lift them.

None of this makes works on paper difficult to own. It means their care is mostly about limiting exposure and choosing the right materials around them.

Light and display

Light is the greatest long-term risk to works on paper on display. Both ultraviolet and visible light fade many pigments, dyes and inks and yellow the paper itself, and the effect accumulates over every hour of display. NEDCC's guidance on protecting collections from light explains the principles; for a specific work, a conservator can advise on appropriate light levels and how long it should be shown before a rest period.

Many collectors manage this by rotation, displaying a sensitive work for a set period and then storing it in the dark while another takes its place. Other measures include UV-filtering glazing, hanging works on walls that never receive direct sun, drawing blinds when rooms are empty and avoiding picture lights that concentrate light on the sheet. Richly coloured watercolours, works in felt-tip or other fugitive inks, and colour prints deserve the most caution.

A simple display log, noting when each sensitive work went up and came down, makes rotation practical and gives a conservator useful information later.

Handling works on paper

Most accidental damage to paper happens in the hands. A sheet lifted by one corner can crease or tear under its own weight, and fingers leave oils that may later show as stains. A few habits prevent most of it.

Storing works on paper

Unframed works are best stored flat, in conservation-grade folders inside closed boxes, often called solander or print boxes. Sheets can be interleaved with a suitable tissue, although the right tissue depends on the medium, and pastels and charcoals often need a window mount or a sink mount so that nothing rests on their surface.

Folders, boxes and interleaving should all be of conservation-grade material. Ordinary cardboard, brown envelopes and household paper are acidic and will discolour the works they touch. Boxes should be kept off the floor and away from exterior walls, pipes and radiators, in rooms without the humidity swings of basements, attics and garages.

Oversize works, such as large prints and drawings, are harder to store well and are often the ones kept rolled or in unsuitable frames. They are worth discussing with a conservator or a storage specialist rather than improvising.

Framed works on paper that are not on display should be stored upright and supported, with padding between frames, rather than stacked flat on top of one another.

Humidity, mould and pests

Paper absorbs moisture readily, and damp conditions bring particular risks. Mould can grow on paper and on the starch pastes and sizes used in its making and mounting, and the reddish-brown spots known as foxing are associated with damp. Very dry conditions carry their own risks for some materials. The right range depends on the object, and a conservator's advice for a specific collection is more reliable than any general figure.

If mould is found, the affected work should be isolated in a clean enclosure and a conservator contacted. It should not be brushed off indoors, since spores spread easily and some moulds pose a health risk. Insects such as silverfish feed on paper, glue and starch paste; grazed areas, small holes or droppings are reasons to inspect neighbouring works and seek advice.

Water is the most urgent case. After a leak or flood, wet works on paper need a conservator quickly, since mould can develop soon after paper becomes damp and wet sheets tear easily when handled.

Framing and when to call a conservator

A framed work on paper should have a conservation-grade mat and backing, reversible hinges, and glazing held clear of the surface. Acrylic glazing is generally avoided for pastels and charcoals because of static. Older frames often contain acidic boards, tape or dry mounting, and are worth having opened and assessed.

Some problems should be left to a paper conservator from the start: tears, flaking or powdering media, stains, pronounced cockling, active mould, and old tape or adhesive on the sheet. Removing tape is a common temptation and a common cause of skinned or torn paper. A conservator can remove it safely and can also advise on whether treatment is needed at all, since some old marks are stable and better left alone.