Care for works on paper

Works on paper, drawings, prints, photographs, watercolours, manuscripts, and archival documents, are among the most vulnerable objects in any collection. They respond to light, moisture, handling, and the materials they touch. The method below is built around one decision rule: when in doubt, reduce change. Paper wants a stable environment, low light, and minimal handling. Everything else follows from that.

This page is not connected to the former TSB Bank Wallace Arts Centre or the James Wallace Arts Trust, and does not speak for them. It is an independent guide.

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The one rule that governs everything

If you can control three things, light, humidity, and handling, you have solved 90% of paper conservation.

Every other factor (framing, storage, pests, transport) is a variation on those three. When you are unsure what to do, ask: Does this action reduce light, stabilise humidity, or reduce physical contact? If the answer is no, do not do it.

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Light: the most common cause of irreversible damage

Light damage is cumulative and permanent. It cannot be reversed, only prevented. The damage is caused by ultraviolet (UV) radiation and, to a lesser extent, visible light. UV fades pigments and darkens paper fibres; visible light adds to the same effect, though more slowly.

The standard threshold used by conservators is 50 lux for works on paper, and no more than 3,000,000 lux hours per year (Canadian Conservation Institute, 2017). For comparison, a typical living room in daylight can reach 300-500 lux. That means a work on paper placed in direct sunlight for a few hours a day can exceed a year’s safe light exposure in a single afternoon. Use UV-filtering glazing (museum glass or acrylic with UV protection) and keep works off walls that receive direct sun. If you cannot control the light, rotate the works: display a piece for three months, then rest it in darkness for nine months. The rule of thumb is that every 100 lux halves the safe display time.

Humidity is the second threat. Paper is hygroscopic: it absorbs and releases moisture, and rapid swings cause cockling, warping and mould. The recommended range for mixed collections is 45-55% relative humidity, with a 24-hour fluctuation of no more than ±5%, per the Canadian Conservation Institute (2020). In Aotearoa, this means avoiding exterior walls in winter, using a dehumidifier in high-humidity rooms, and never placing works above a heater or in a bathroom. A cheap digital hygrometer is the single best investment.

Light is cumulative and irreversible. The international benchmark is 50 lux for works on paper, and no more than 200 lux for most paintings; ultraviolet (UV) radiation should be below 75 microwatts per lumen (CIE, 2004). Even at these levels, light damage is permanent and additive. For works on paper, the practical rule is: no direct sun, no halogen spotlights, and no more than three months of continuous display per year if the work is not behind UV-filtering glazing. For framed works, use UV-filtering acrylic or glass; for unframed works on paper, keep them in archival boxes and limit display to short periods. Rotate sensitive works seasonally.

Humidity is the hidden killer. Paper is hygroscopic; it absorbs and releases moisture, causing cockling, foxing, and mould. The safe range for mixed collections is 45-55% relative humidity (RH), with 50% as the target (National Preservation Office, 2005). Avoid exterior walls and rooms with uninsulated windows; the microclimate near a single-glazed window can swing 20% RH within a day. In Aotearoa, the humid Auckland climate means that a dehumidifier may be necessary in winter; in drier parts of the South Island, the opposite problem, over-dry air, can make paper brittle and should be moderated with humidifiers or microclimate boxes.

Light: UV is the main threat. The Canadian Conservation Institute (CCI, 2017) states that light damage is cumulative and irreversible, and that the recommended maximum for works on paper is 50 lux for 3,000 hours per year (about an hour a day) for highly light-sensitive materials, and 200 lux for low-light-sensitivity materials like works on paper with stable pigments. No direct sunlight, no halogen without UV filters, and no LED strip lights mounted inside the frame.

Relative humidity: The safe band is 45-55% RH year-round (CCI, 2017). Fluctuations are more damaging than a steady reading slightly outside the band. Paper is hygroscopic: it expands and contracts with moisture, causing cockling, warping and cracking of media. In Aotearoa, the practical risk is not desert dryness but coastal humidity, so a dehumidifier in winter and a humidifier in a dry interior winter can be necessary. Do not guess; measure with a digital hygrometer.

Temperature: The lower the better for chemical stability, but human comfort sets the limit. Avoid attics, garages and uninsulated exterior walls. Keep works away from heat sources such as radiators, fireplaces, and direct sunlight.

Light: Keep works out of direct sunlight and away from strong spotlights. UV is the main cause of fading. Use UV-filtering glazing or acrylic for framed works. For unframed works on paper, keep them in archival boxes or portfolios and handle them with clean, dry hands or wear nitrile gloves. Display rotation: rotate works on paper every three to six months, and store the off-display work flat in an archival box between layers of acid-free tissue. For photographs, a 200 lux limit is a reasonable benchmark for sensitive works; for works on paper, the benchmark is 50 lux.

Humidity: The recommended relative humidity for paper is 40-60%, with 50% as the midpoint; avoid fluctuations of more than 10% in a single day. Use a digital hygrometer near the work and monitor seasonal changes. Do not hang works on exterior walls in older homes; in humid climates use a dehumidifier in the room, not a closed cupboard.

Handling: Use two hands, cotton or nitrile gloves for unvarnished surfaces, and never touch the front of a photograph or a pastel. Avoid rolling or folding works on paper; if you must transport them, use a rigid board and tissue.

Storage: Flat files or archival boxes are ideal. If a work must be rolled, roll it with the image facing outwards on an archival tube, and never store works in basements, attics, or near exterior walls. Do not stack works directly on top of one another without protective interleaving.

Light: Total exposure is cumulative and irreversible. The standard rule from the conservation field is 50 lux for light-sensitive works (works on paper, watercolours, photographs) and 200 lux for general collection displays. UV-filtered glazing and LED lighting are recommended. Avoid direct sunlight at all times.

Humidity: The safe band for paper is 45-55% relative humidity. Fluctuation is more damaging than a steady level slightly outside the band. Use a hygrometer and avoid placing works near bathrooms, kitchens, or exterior walls.

Temperature: Keep works away from heat sources, and avoid sudden changes. Stable room temperature is the goal; there is no single “correct” temperature, but a range of 18-21°C is commonly cited.

Framing: Use archival, museum-grade materials: UV-filtering glass or acrylic, acid-free mats, and conservation-grade backing boards. Do not let the artwork touch the glazing; use a mat or spacer. For works on paper, hinging with Japanese paper and wheat starch paste is the conservation standard; pressure-sensitive tape is never acceptable. For works on canvas, framing is optional but if framed, the canvas should not touch the glass. For Māori and Pacific works, framing and display decisions should be made in consultation with the artist or community where possible, as some materials and images carry cultural protocols.

Pests and pollutants: Keep works away from food, smoking, and areas where insects or rodents are active. Silverfish and cockroaches are the most common threats to paper in Aotearoa; their presence is a sign to check storage areas and consider traps or professional pest control. Do not use mothballs or naphthalene near artworks; they can damage frames and paper.

Storage: Use acid-free or archival-quality boxes, folders, and tissue. Avoid basements and attics where humidity and temperature fluctuate. Do not stack works flat unless interleaved with acid-free tissue, and never store works directly on concrete floors. For large works, roll them around a rigid tube with the image side facing outward, wrapped in acid-free tissue, and store horizontally or vertically with support.

Handling: Always wash and dry hands before touching works. Wear clean cotton or nitrile gloves for photographs, pastels, or any work with a fragile surface. Support the work with both hands or a rigid board when moving it. Never touch the surface of a painting or drawing; handle only the edges or the back. Avoid eating, drinking, or smoking near works. Remove rings, bracelets, or anything that might scratch. Use two people for anything larger than a metre.

Display: Hang works away from direct sunlight, heat sources, and high-traffic areas. Use picture hooks and hanging systems rated for the weight; for heavier works, use two hooks and a wire rated to at least three times the weight. Use UV-filtering glass or acrylic in frames when possible. Keep works away from exterior walls in humid climates; if you must hang on an exterior wall, use a spacer frame to allow airflow. For unframed works on paper, display only under glass with archival matting; never display works directly under a skylight or in a room with strong afternoon sun.

Light: Total light exposure is cumulative and irreversible. The international guideline for light-sensitive works on paper is 50 lux (about the light of a dim hallway) and no more than 50,000 lux-hours per year (Canadian Conservation Institute, 2017). Use UV-filtering glazing or acrylic, and keep works out of direct sunlight. If you cannot measure lux, use the hand-shadow test: if a hand held between the light source and the work casts a sharp shadow, the light is too strong. Rotate works every 3-6 months to limit cumulative exposure.

Humidity: The safe band for paper is 45-55% relative humidity, with slow changes. Rapid swings cause cockling and dimensional change; sustained high humidity invites mould; sustained low humidity makes paper brittle. The Museum of Fine Arts, Boston, recommends 45-55% RH and 18-22°C for mixed collections. Use a hygrometer to monitor; avoid placing works near exterior walls, vents, fireplaces, or bathrooms. If humidity fluctuates, a microclimate frame with sealed backing and desiccant is a practical intervention.

Handling: Always handle works on paper with clean, dry hands or wear nitrile or cotton gloves. Support the full sheet with both hands or a rigid board. Never touch the surface; oils and acids from fingers cause permanent marking. Do not use tape, pins, or adhesives on the work. For large works, two people carry it flat, and avoid rolling unless the paper is designed for it; rolled works must be stored in archival tubes, never resting on the rolled edge. Never use self-adhesive tape, pressure-sensitive tape, or rubber bands near the artwork.

Storage: Store flat in acid-free folders or boxes, never rolled for long periods. If rolled, roll with the image side out onto an acid-free tube, and support the entire length. Separate works with acid-free interleaving tissue. Keep storage areas dark, cool, and stable; avoid attics and basements. Use a microclimate box for high-value works if humidity fluctuates. For framed works, store upright with rigid backing boards, never flat under heavy objects. Keep storage boxes off the floor to avoid flood and pest risk. Do not stack framed works flat unless absolutely necessary; if you must, use soft padding between frames and keep the stack small.