Conservation advice: Paintings

Paintings are complex, layered objects; there is a support (textile or solid), often preparation/ground layers, paint layers (most often oil or acrylic) and then possibly a varnish or other surface coating. Please see the Works on Paper webpage for watercolour paintings.

Deterioration and damage of paintings, in any or all of these layers, can be due to a single or combination of intrinsic and extrinsic factors.

Intrinsic factors generally relate to the choice of materials made by the artist, and are internal to the manufacture of the painting. They include:

• Using materials which later prove to be inherently chemically unstable or fragile
• Deliberately using ephemeral materials
• Using a mixture of materials which are incompatible

Extrinsic factors are those which are applied externally. They include:

• Poor environmental conditions: light, humidity, temperature, pollution
• Mechanical stresses: impact, vibration, handling, accidents/vandalism/neglect
• Biological damage: insect, fungal, microbial attack
• Previous (poor or aged) restoration

Any damage to (or poor condition of) a painting should be addressed by a paintings conservator in order to prevent further types of damage or continuation of damage. 

Canvas paintings (textile supports) have the most problems, these may include canvas slackening, denting or tearing and cause associated paint damage. Canvases become slack in humid weather and tighten in dry conditions. Repeated changes in humidity and temperature can cause deterioration and weakening of the canvas so it is important to keep the climate as stable as possible. 

Paintings on solid supports (such as plywood, wood panels, Masonite or cardboard) are usually stronger and suffer from less damage than those on textile supports but can still be bent, broken, cracked, warped, layers separate or in the case of cardboard become too weak to support a paint layer. 

Oil paint is reasonably tough and most paintings are in good condition, but in some circumstances can crack. Much paint cracking is stable but if paint becomes loose or begins to lift (as a result of impact, environmental changes or inherent instability), the paint is in danger of falling off or being caught and pulled off by something and should be treated by a conservator. Water damage to a canvas painting is one of the most difficult to treat when the canvas shrinks but the paint doesn’t and it separates from the canvas and sits in a raised tent form. 

Since the 1960s, acrylic paintings are also common. They often look similar to oil paintings but have very different solubility properties affecting paint cleaning, varnishing and varnish removal and require specialist treatment.

Framing and hanging

Aside from the aesthetic, framing paintings is important to give the painting support and protection around the edges. If the painting is nailed into an existing frame, be careful when removing (use a piece of card to avoid damaging the back of the painting). These nails should be replaced by a bracket/screw system for ease of removal in future. 

Framing also allows glazing with anti-reflective, laminated glass or acrylic (requires a spacer in the frame to ensure this glazing is not in direct contact with the painting). This is recommended for protecting paintings against impact and pollution. A backing board of non-acidic cardboard or foamboard can prevent accidental damage from the back.

It is recommended that a painting, unless very small, has two points of hanging to distribute the weight and in case one should fail. D-rings are recommended, but if using hanging wire make sure it is very securely attached to the painting and still use two hooks on the wall. Ensure appropriate weight loading (kg rating) and suitability for type of wall. The depth, gauge and number of screws or nails into the frame and wall (if direct fixing using a hook or installing a picture rail) must also be adequate.

Hanging devices should be fixed into the painting’s frame and not directly into the support if at all possible. For displaying un-framed rigid supports eg. bark paintings, supporting brackets holding the weight from below, or a specific non-restrictive ‘brace’ may be created – please obtain the services of a qualified framer/conservator.

Storage and Display Environment

Because the support layers of paintings are commonly responsive both to moisture and very dry conditions, a stable environment where there are no significant fluctuations in temperature and relative humidity (displayed inside the house on inner walls, and not stored in attics, sheds or garages) will help to minimise deterioration. Don’t display paintings near heaters or in-line with air-conditioning vents. 

Paintings should be displayed out of direct sunlight at all times (be careful as this differs with changing seasons). Ideally, UV content should be removed or be as low as possible. Choice of suitable artificial light sources (eg. tungsten halogen, low UV emitting fluorescent, LEDs) or filtering may otherwise be possible either at the light source (UV and IR filters), or at the painting (glass or acrylic glazing). 

Paintings without glass or acrylic should never be displayed or stored in areas where particulate pollution is generated, eg. kitchens, in the vicinity of smoking or fireplaces. 

To dust the surface of a painting in good condition use a wide, soft haired brush (hake brushes are available at art stores) and brush lightly across the surface in a horizontal and then vertical direction. Don’t use a cloth as it may catch on textured paint and never use water or cleaning products. If there is flaking or fragile paint, do not dust. Darkening of the image by a layer of ‘grime’ or discoloured varnish may be reduced with careful surface cleaning by a conservator.

Handling and transport

Unless it has no frame, a painting should be handled, transported and stored in its frame. Generally paintings should be carried vertically, by two people if necessary.  Always carry a painting by the strongest areas – on the frame or stretcher side members, not the corners or along the top. If a painting/frame is too fragile to carry on its own, it should be moved horizontally on a supporting board. Canvas paintings should not be stored face-up horizontally for a length of time as gravity may cause sagging and associated denting against the stretcher or any cross-braces. Vertical is best.

Never place the front surface of a painting directly on something fibrous like felt or carpet as textured paint layers may catch. 

To transport, keep framed but if possible remove or tape across any single pane glass to prevent shattering. Never wrap a painting directly in bubble-wrap or a fibrous material if there is a chance it will touch the painted surface as it may mark or catch. Firstly, wrap it in acid-free tissue paper, or soft, smooth fabric such as a sheet or inside a pillowcase (not flannelette and no loose threads), or between two rigid boards slightly larger than the painting, and then bubble wrap. Don’t allow any objects to rest against the front or back surface of the painting. Travelling frames and crates are generally a safer option for long distance travel - an experienced art transport/courier company should be consulted.

The Australian Institute for the Conservation of Cultural Material provides a directory of conservators in private practice. You can use the directory to find someone in your region with the expertise to provide qualified care of your memorabilia.