Location is crucial for preserving the condition of antique paintings, ideally away from heat sources and damp environments to prevent mold.
Hang a picture securely, in a spot that is neither damp, nor above a fire or radiator, nor too bright. Make sure air circulates around it by letting it lean away from the wall at the top. If a picture is to hang on an exterior wall, glue corks to the lower corners of the frame for extra insulation.
Use metal picture wire and one or two steel or brass picture hooks depending on the size and weight of the piece. Heavy, glazed pictures might need extra support – at the base on brackets fixed to the wall. Screw eye hooks into the frame, never into the stretcher or backboard. With a heavy picture, put a pair of hooks on each side, fastening the wire to the lower pair and running free through the upper pair. Then, if one hook gives way, the painting won’t fall.
Whether you learn to mount and frame pictures yourself or go to an expert, it is important to understand how framing and mounting help to conserve a work of art. Always set oil paintings in a deep frame. To protect the edges of the painting, line the frame with velvet ribbon or inert foam-rubber strips. If the rebate is too deep, pad it out with cork or balsa wood strips. If it is too shallow, build up the frame with strips of wood.
Mirror plates or brass plates screwed into the frame and overlapping the stretcher hold picture and stretcher firmly in place.
Oil paintings don’t need glaze, as their varnish protects them already.
Always mount works of art on paper on acid-free board. Check whether an existing mount is acidic by looking at the bevelled edges of the ‘window’; if there is a brown stain around the line of the window, then the board is probably poor quality wood pulp and needs replacing.
The mount separates the glass from the picture; this not only prevents the work from rubbing and from sticking to the glass but also provides a thin layer of air, which deters mold.
The frame must be deep enough and strong enough to hold the backing board, mounting board and glass. The backing board keeps dust and insects out – especially if sealed with gummed paper tape around the edges – and secures the picture firmly in its frame. As it is likely to be made of wood or hardboard and acidic, it should not touch the back of the picture and can also be coated with polyurethane varnish or covered with acid-free paper.
Paintings on paper need glazing, as they don’t have a protective layer of varnish. Glass also keeps out insects such as silverfish, thunderbugs or thrips, which not only feed on the paper, but may die and leave stains.
Acrylic (Perspex) sheeting is lighter and less fragile than glass but scratches easily and attracts dust more readily. ‘Clip-frames’, cuts of glass and (acidic) hardboard clipped together are not dust and insect-proof so they’re unsuitable for long-term mounting.
Most pigments used for works of art on paper are extremely sensitive to light and fade dramatically; for this reason, never photocopy precious items. Oil paints are less likely to fade but will dry and crack with heat from direct light. Beware of ‘purpose-made’ picture lamps; the bulbs are usually ordinary incandescent lights which will overheat the area they illuminate and therefore cause damage. Even cool beam lamps should not be left on for long.
Store framed pictures in a cool, dark, clean, dry place. Remove hooks or any projections that may harm the frames or pictures. Stand the pictures on wooden blocks to raise them above floor level and place acid-free board between each. Ensure the largest, heaviest pieces take the weight at the back and place a weight in front of the stack. Cover the lot with a clean sheet – never polythene as this encourages mold. Store unframed works of art on paper in an acid-free box or folder. Place acid-free tissue between each work and store horizontally. Sulphur vapour from certain substances, including some plastic folders, causes paper to discolour.
Beyond removing surface dust with a soft squirrel brush, or dusting the case of a miniature, the cleaning of pictures, whether of oils or on paper, is a job for the professional.
Conservation of oil paintings
Leave conservation work of any sort to a professional. For instance, go to a restorer at the first signs of paint lifting off or flaking, for once it starts, deterioration can be rapid. Remove the painting from the wall and lay it face up, so that the paint does not fall off. The varnished surface on oil paintings often yellows with time and may then need removing (without dissolving the paint layers beneath) and renewed. A whitish bloom on the surface of an oil painting, brought on by a damp atmosphere, can be treated. Bitumen, used in some 19th century oils, forms deep cracks with age. These are difficult to treat beyond a little filling and retouching to make the problem less obtrusive.
Conservation of works of art on paper
For most works of art on paper – including watercolours, drawings, prints, photographs and books – common conservation problems involve the paper rather than the printing or painting process. The more acidic a paper is the quicker it deteriorates – turning brown and crumbly in light, or in damp conditions developing mold or little brown spots known as ‘foxing’.
Overall discolouration is usually due to a low-grade paper which becomes increasingly acidic with age. The problem is aggravated if the paper is in contact with acidic materials such as cheap mounting board. Displaying or storing pictures, stamps or books in acid-free materials is an absolute priority.
The light-sensitive silver salts in photographs are particularly vulnerable to chemicals. Ideally, display photographs in albums with highly alkaline paper and mounted on corner mounts or stamp hinges, or in closed frames or transparent, acid-free polyester or polythene envelopes.
Stains and foxing of watercolours can sometimes be professionally removed by a skilled washing process. The carbon printing ink used for books and most European prints is quite stable, and can also be washed by a conservator without harming its density.
Display books on a painted or varnished shelf, and ideally lined with acid-free card. Don’t forget that strong light will fade the spines. If the shelves are within a cabinet, make sure there is adequate ventilation.
Book-ends should be as large as the books they confine so that pressure is spread equally over the surface. Don’t pack volumes too tightly together on a shelf. To remove a book, reach over the top of it and ease it out from the back of the shelf, or prat it from the volumes either side and grasp it by the sides.
Boards that have fallen off of the sides of books can be temporarily held in place by tying cotton or crepe bandage around the book from top to bottom, which will not be visible when the book is on the shelf with other volumes. Rebinding may devalue a rare book. A skilful craftsman can ease off an old spine, rejoint the original boards and reattach the original spine. But even this process, known as ‘rebacked with spine laid on’ may reduce the value. If broken bindings are repaired or renewed, keep the original pieces as documentary evidence.
Only remove a stamp from its envelope or card if you are sure its post mark is of no value. Never steam, but ‘float’ stamps off in lukewarm water and then dry between layers of white blotting paper. Any mounting material that actually touches the stamps must be acid-free. Chemically inert PVC sleeves are useful for mounting complete envelopes or cards, but make sure they do not seal completely as condensation may form. Loose-leaf albums combined with transparent photo=mount corners are ideal, with stamps displayed on one side of each leaf only so that facing pages do not rub or catch.
Never use adhesive tape or the gum of the stamp itself to fix it to a surface, but gummed stamp hinges with the minimum amount of moisture at the top of the stamp. You should be able to peel the stamp off again without damaging it. Don’t use hinges for mint stamps, as this could reduce their value. Use Hawid plastic mounting strips instead.
With thanks to Readers Digest.
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