Care and conservation of prints, drawings and watercolours

Works of art on paper appear in almost every private or public collection and cover a vast range, both in subject matter and value. In Europe, paper has been in common use as a picture support since the mid 15th century, when printing created a huge new demand for it, and it remains a popular material for artists. Paper is fundamentally made of cellulose in the form of finely broken down plant fibres. In its purest form, cellulose is extremely durable, but preparation methods, additives and impure sources (for example, unpurified wood pulp) can cause the paper to become weak over time. Artists’ materials may also be unstable. Pigments can fade, inks can corrode the paper, pastels and charcoal get smudged, and thick paint like oils and gouache can flake.

What can go wrong?

Works of art on paper such as prints, drawings and watercolours can be damaged by light, extreme or fluctuating temperature and relative humidity, pollution, pests, and poor handling, storage and mounting.

  • Watercolour paintings with a strange colour balance, or ink drawings which have lost their detail have usually been damaged by light. The original colouring can often be found at the edges where the image has been protected from light by a windowmount. As well as fading media, exposure to light damages the structure of the paper itself.
  • Temperature affects the speed of the chemical reactions leading to the deterioration of paper. An increase in temperature increases the rate of deterioration, leading to brittleness and darkening of the paper.
  • The brown spots called ‘foxing’ are often a sign of a poor environment. These stains are caused by bacteria or mould which generally grows on acidic paper when the humidity is high, or when there are metallic particles in the paper as a result of the papermaking process.
  • Insect damage (such as holes in the paper or ’grazed’ surfaces) and mould are indications of an uncontrolled environment in which humidity and temperature are high.
  • Atmospheric pollutants, for example sulphur, can contribute to the breakdown of paper; they can also change artists’ colours.
  • Contact with boards containing unpurified wood pulp may turn paper brown and brittle. ‘Mount burn’ describes the brown marks around the edge of an image where an acidic windowmount has ‘burnt’ the paper. Brown ‘air-burn’ marks can also form through gaps in old wooden backboards. Poor quality mounting and framing damages more works of art on paper than any other agent.
  • A certain amount of cockling or undulation is usual in handmade paper, but if the work of art is badly distorted, wrinkled or even torn at the corners it has probably been stuck down at the edges. Paper moves naturally in response to changes in humidity and it is best not to restrain it.
  • Yellow or brown stains on paper, especially in regular patches, can be due to the glue or adhesive tapes used to fix the picture into a mount. Self-adhesive tapes are particularly damaging because the adhesive creeps into the paper and is then extremely difficult to remove.
  • Avoid the temptation to restore works of art on paper yourself. Dubious traditional remedies such as using bread crumbs to clean off dirt, or the use of commercially produced tapes to repair tears will do more harm than good. Well-meaning attempts have the potential to cause significant damage which can add to the cost of professional treatment or affect the value of your work of art.

An accredited paper conservator will be able to advise on the causes of damage as well as suggest appropriate treatments and provide recommendations for ongoing care.

What you can do

Environment

Protect framed prints, drawings and watercolours from daylight. Avoid south facing light and use ultraviolet (UV) filtering glass for framing. Try not to hang pictures directly against the interior of the outside wall of a building: the comparatively low temperature can cause condensation and mould growth inside a frame. Conversely, a radiator or spotlight dries the air out, and concentrates dirt by convection currents.

It is best to keep works of art on paper in a cool, stable environment. Museums aim for a temperature of 16-19˚C and relative humidity of 45-60%. This may not be possible within a domestic setting, but a low and stable relative humidity (less than 60%) will help to slow the deterioration of the paper and reduce the potential for damage from pests and mould.

Handling

When handling works of art, you should touch the paper as little as possible and keep your fingers away from the image.

Pastel and charcoal drawings need extra care because the image may smudge easily: you could consider keeping them permanently framed within a mount that has been rebated to prevent any static or friction. Contemporary prints should not be handled directly either, because their immaculate paper is easily marked with oil and moisture from skin. Keep them in a mount or acid-free paper folder.

Storage

If your prints, drawings and watercolours are not on display, the best way to keep them is in a plan chest or a specially designed case such as a Solander box. The works of art are protected from light and dirt and can be placed in further protective folders inside the box or plan chest for ease of handling. Boxes, folders and portfolios are available in conservation quality materials (inert and sometimes with an alkaline reserve) and should be stored horizontally. Translucent acid-free tissue paper is good for interleaving or wrapping small items. Plastic sleeves are not generally suitable for storing works of art on paper.

When choosing a suitable storage area, bear in mind the need for a stable environment and avoid damp cellars and uninsulated attics. Items in storage should be checked regularly for signs of damage.

A conservator will be able to advise on suitable storage materials, provide estimates for the packing of collections, or carry out a re-housing programme.

Mounting and framing

Good quality mounting and framing is one of the most effective methods of preserving and caring for works of art on paper. Guidance is available in the leaflet ‘Guidelines for conservation mounting and framing of works of art on paper’, (see www.conservationregister.com). As a minimum guide you should think about the following points relating to light and methods of framing.

Light damage is cumulative and irreversible. UV filtering glass or acrylic is highly recommended to protect against the most damaging light. Acrylics such as Perspex™ are useful because they are light and unlikely to break on impact. However, these materials do scratch more easily and because of static, should never be used to glaze pastels, chalks, charcoal or any other friable material.

Your framer should be aware of ‘Museum’ and ‘Conservation’ levels of framing and should be able to answer ‘yes’ to the following questions:

  • Will the frame have enough depth in the rebate to accommodate the glazing, windowmount, undermount, isolating layer and the backboard, and the strength to take hanging fittings (secured to the frame not the backboard)?
  • Will both the windowmount and the undermount be made of Cotton Museum Board (100% cotton fibre) or Conservation Board (chemically purified wood pulp core or cotton fibre core)?
  • If there is no windowmount, will the glazing material be spaced away from the picture surface?
  • Will the work of art be attached to the undermount only and using gummed, white paper hinges?
  • Will there be an isolating layer of inert polyester between the undermount and backboard, or will a pH neutral conservation backboard be used?
  • Will the frame be sealed with gummed paper tape?

A paper conservator can help you find a qualified framer.

Consulting a conservator

There is much that individual owners or custodians can do to protect works of art on paper, but when damage has already been done it is advisable to consult an accredited paper conservator. Conservators are trained to understand the physical and chemical composition of paper and associated media, and their methods of deterioration. With professional treatment, the condition of both paper and image can normally be stabilised so that their deterioration is slowed. Although faded colours cannot be restored to their original brightness and severe paper staining may only be reduced, most damage can be corrected by a skilled conservator who will also take into account the history of the item and the way that it is used when deciding on the appropriate method of treatment. Some of the ways in which a conservator can help you are:

  • Providing advice on suitable environmental conditions and lighting both for storage and display.
  • Carrying out condition surveys of individual works of art or entire collections.
  • Providing and discussing recommendations for treatment including cleaning, stain reduction, removal of self-adhesive tapes, repair of tears, and deacidification.
  • Devising ‘good housekeeping programmes ‘for storage areas, including cleaning routines and pest management.

Use the Conservation Register to Find a conservator.

© Icon, the Institute of Conservation 2011.

This article offers general guidance and is not intended to be a substitute for the professional advice of an accredited conservator. The views expressed are those of the author or authors, and do not necessarily represent the views of the Institute of Conservation.

The Institute of Conservation would like to acknowledge use of the MGC publication 'Ours for Keeps' and the IPC/TNA publication 'Caring for your prints, drawings and watercolours' in the preparation of this text. The Institute of Conservation and its partners accept no liability for any loss or damage which may arise if this guidance is followed.

The Institute of Conservation would like to acknowledge the support of The Royal Commission for the Exhibition of 1851 in the production of this guidance information. Further information on The Royal Commission for the Exhibition of 1851 and its work is available at www.royalcommission1851.org.uk.