How to Protect Art and Antiques During a UK Heatwave

The UK has experienced exceptional heat this year, with temperatures reaching 38°C. While these conditions can be uncomfortable for us, prolonged heat can also place unexpected stress on your art, from oil paintings and watercolours to prints, sculptures and antique furniture.

While museums, galleries and historic houses take precautions during extreme heat, private collections face many of the same risks. Heat, sunlight and changing humidity can all affect sensitive materials in different ways.

In this guide, our conservation team explain the key risks to look out for and share practical steps you can take to protect your precious items during a heatwave. If you are concerned about how the heat may be affecting your art, antiques and decorative objects, please contact our experts for professional advice.

How Does Art React to High Heat & Humidity?

High temperatures and changes in relative humidity can place artworks and delicate objects under stress. Heat can soften adhesives and finishes, dry out materials and contribute to distortion, while fluctuating humidity causes materials such as wood, canvas and paper to absorb or release moisture, making them expand and contract.

Because artworks and antiques are often made from several different materials, each reacting at a different rate, these changes can lead to cracking, warping, lifting surfaces and weakened joints. Warm, humid conditions can also increase the risk of mould.

The British summer can create particularly challenging fluctuations when trying to keep your artwork in a stable environment. A room may become extremely warm during a sunny afternoon before cooling considerably overnight, particularly when windows are opened in the evening. In older houses, conditions can also vary significantly from room to room. A ground-floor drawing room may remain relatively stable, while a converted loft or room with skylights can experience periods of extreme heat.

During hot weather, we recommend checking the rooms where your most vulnerable artworks are displayed at different times of day. If a space becomes particularly hot, consider closing blinds or shutters to reduce solar gain and, where safe to do so, moving vulnerable pieces to a more stable room until temperatures return to normal.

If you notice any new or unusual changes to an artwork or antique during or after a period of hot or humid weather, contact our conservation team for advice. Early assessment can help identify whether the object is at risk and prevent minor changes from developing into more serious damage.

Pollution from Open Windows

When a room feels unbearably warm, the instinct is often to open every available window. For collections, however, it is worth thinking about when and where you ventilate the space. 

During the hottest part of the day, opening windows can actually allow hotter outdoor air into a comparatively cool building. Where possible, keeping windows shaded and closed while the outside temperature is higher, then ventilating when temperatures fall in the evening or early morning, can help limit extreme indoor temperatures.

In London and busy urban areas, an open window may provide welcome airflow but can also allow outdoor pollutants and fine particles from traffic into the room. Hot conditions can also contribute to elevated levels of ground-level ozone. For artworks displayed close to busy roads, it is important to balance the need for ventilation with the risk of contamination. If necessary, consider temporarily relocating vulnerable artworks to a cleaner, more stable part of the property while these conditions persist.

In rural areas, open windows may introduce dust, pollen and insects. In seaside homes, air entering from outside may carry salt-containing aerosols. However, none of this means that windows must remain permanently closed. 

Ventilation should be considered as part of the overall environment surrounding a collection. Where possible, ventilate during cooler periods, avoid leaving vulnerable objects immediately beside open windows and inspect frames, shelves and exposed surfaces periodically for accumulated dust, debris or pollution. 

If you notice surface changes such as discolouration or a build-up of pollutants, consider speaking to our team about professional cleaning. We do not recommend attempting to clean paintings, frames or valuable objects at home, as even seemingly gentle cleaning methods can result in accidental damage.

Display Conditions & Sunlight Exposure

Strong sunlight can be particularly damaging to artworks. Direct sunlight can raise the surface temperature of an artwork considerably, while prolonged exposure to ultraviolet light can contribute to fading and changes in sensitive pigments, dyes and paper.

Watercolours, prints, drawings, photographs and textiles can be especially light-sensitive. During periods of strong summer sun, consider how light moves through the room throughout the day. An artwork that receives little direct sunlight in winter may suddenly be exposed for several hours during summer.

This can be particularly noticeable in south and west-facing rooms, conservatories and properties with large modern areas of glazing. Even in traditionally cooler stone houses, an artwork positioned in a shaft of afternoon sunlight can experience conditions quite different from those elsewhere in the room.

Our conservators advise to:

• Keep paintings and works on paper away from prolonged direct sunlight
• Use blinds, curtains or shutters during the brightest and hottest parts of the day
• Pay particular attention to south and west-facing rooms
• Avoid placing vulnerable objects immediately beside large windows or rooflights
• Consider UV-filtering glazing or window films where appropriate
• Check framed works periodically for fading, distortion or condensation

If an artwork is particularly valuable, fragile or light-sensitive, our team can advise on suitable display conditions and protective glazing.

Fans & Air Conditioning Risks

When a room becomes very hot, switching on a fan or air conditioning may seem like the obvious solution. However, rapid environmental changes can sometimes create additional stress. Avoid directing a powerful fan or air conditioning unit straight towards a painting, antique or other sensitive object. Concentrated airflow can create localised changes in temperature and humidity, while rapid cooling may cause materials to respond too quickly.

Where air conditioning is used, aim for a stable and comfortable environment rather than making the room as cold as possible. Gradual changes are generally preferable to repeated swings between very hot and very cool conditions.

Portable air conditioning units can also produce condensation or require water collection. Position them carefully so that leaks or moisture cannot affect nearby artworks, furniture or flooring. Fans are best used to encourage gentle air circulation around a room rather than blowing continuously onto individual objects.

Simple Precautions During a UK Heatwave

You do not need museum-standard environmental controls to take sensible preventive measures at home. Before and during very hot weather, our best advice is to:

• Close curtains, blinds or shutters where strong sunlight reaches artworks
• Keep particularly sensitive pieces away from direct sun
• Consider keeping windows closed during the hottest part of the day, then ventilating when outside temperatures fall
• In polluted urban areas, be mindful of prolonged ventilation from windows directly overlooking busy roads
• In coastal properties, keep vulnerable objects away from open windows where they may be exposed to salt-laden air
• Avoid positioning fans directly at artworks or antiques
• Use air conditioning gradually rather than creating sudden temperature changes
• Check portable cooling equipment for condensation or leaks
• Avoid unnecessary handling or moving of fragile objects
• Keep internal doors open where appropriate to reduce pockets of extreme heat
• Check attics, conservatories, garden rooms, which can become considerably hotter
• Look over vulnerable artworks and furniture during and after prolonged hot weather

For significant collections, environmental monitoring can be useful. Small temperature and relative humidity monitors can help identify rooms that experience particularly large fluctuations and inform longer-term decisions about where vulnerable objects should be displayed.

Monitoring can be especially worthwhile in properties that behave differently according to the weather: a London townhouse affected by solar gain and urban pollution, a country house with cool ground-floor rooms and hot attics or a coastal property where humidity changes with the weather.

When Should You Seek Professional Advice?

Some movement and cracking can occur naturally as artworks age, but new or rapidly developing changes should be assessed. Look out for lifting or flaking paint, fresh cracks, slack canvas, distorted paper, lifting veneers, corrosion or mould.

Avoid attempting to clean, flatten or repair affected areas yourself. A conservator can identify the cause and determine whether treatment, stabilisation or monitoring is appropriate. If one object has been affected by extreme conditions, it is also worth checking others displayed in the same room for signs of environmental stress.

If you are concerned about an artwork or antique following a period of extreme heat, contact our conservation team by filling out the form below or calling 0207 112 7576 for professional advice on conservation, storage and display.