Accidental breakage is probably the highest risk for damaging ceramics and glass objects. Luckily, it’s also easy to avoid.
Ceramic and glass objects are not affected by bright light or normal changes in temperature. The adhesives used on restored pieces, however, discolour or weaken with strong light or water.
Make sure your hands are clean and dry before handling anything as greasy fingerprints can leave indelible marks. Wearing cotton gloves while handling china and glass reduces grip. Pick up an item by the soundest part – never the handle – support the base. Watch out for loose parts such as lids, and weaknesses caused by restoration and cracks.
A cabinet/shelf for displaying china or glass must be stable. Cur felt or chamois-leather pads to fit beneath the base of an item to protect the shelf or table. Put plants or cut flowers in a separate container within a vase, with a protective pad between, to prevent water stains.
Only sound, uncracked plates should be wall-hung. Use acrylic or plastic-coated fittings, adjusted to fit the plate.
Use an artist’s paintbrush to remove dirt and dust from any incised or delicate relief decoration before washing. Wash most glass and ceramics in warm water with a little non-ionic or mild household detergent added. Never put fine glass, including modern lead glass, pottery or antique ceramics in a dishwasher.
Before washing fragile objects, place a cushioning material
in the base of the washing up basin and over the taps. Wash and rinse items one at a time and put them to drain for a few moments on a towel. Dry immediately.
Glazed, low-fired earthenwares (delftware, faience and maiolica, etc) may have an unglazed foot-rim, or cracks or chips which expose the porous surface beneath the glaze. Don’t immerse these items – it is safer to wipe them with cotton wool moistened in the detergent water. Other items requiring special care to dust regularly, are:
- crizzled glass, a network of fine surface cracks, then aggravated by moisture;
- any unglazed, low-fired pottery – water, together with any impurities in it, will be absorbed into the porous body;
- objects with metal or ormolu fittings, or mended with iron rivets;
- items with gold leaf or delicate overglaze decoration which might flake easily;
- ancient or excavated glass or ceramic glazes with a flaking iridescence – don’t try to scrape or clean the surface.
You may be able to shift ‘tidemarks’ from glass, with a solution of denture cleaner and warm water, or with acetic acid (or vinegar). Leave either in the glass for 24 hours, then rinse, drain and dry thoroughly. Methylated spirits or pure alcohol can clean alcohol-based perfume bottle stains; change the alcohol every hour or so until the stain has gone.
Ammonia or an ordinary household bleach which contains chlorine will remove stains on most glass. Don’t use it on gilding or fragile decoration. On ceramics, however, this is unsuitable as it may aggravate the stain or cause permanent discolouration. Instead, and only on a soft or hard-paste porcelains surface with no gilt or lustre decoration, obtain 20-volume hydrogen peroxide from a chemist and add a few drops of ammonia. Wear rubber gloves. Dampen strips of cotton wool into the solution, then lay them over the stain or crack and leave for about an hour. Do not let the strips dry onto the surface. To retain the moisture, place it in a plastic bag. You may need to renew the ‘dressings’ several times.
Most enamel-painted decoration on ceramics comes to no harm using this technique, but do not use it on pale blue or greenish-blue 19th century enamels, as they may disappear.
Before dismantling a cut-glass chandelier for a major clean, photograph the piece intact, and work out a system of identifying the lustres so that you know where to put them back. Turn off any electrical connection and do not let water seep into the hollow branches of a chandelier. Wash the lustres in a detergent solution, checking that the metal hooks are sound, rinse thoroughly, and dry immediately to prevent corrosion of the metal. Polish with a soft, lint-free cloth.
Mirrors and Window Glass
Never use commercial glass cleaners for mirrors, stained or leaded glass. The chemicals in them act as a solvent on glass, on a gilt or varnished frame, and on lead or putty. Remove as much dirt as possible from indoor glass with a soft chamois leather. For more stubborn stains wipe with a cloth moistened in warm water with a few drops of methylated spirits and some mild household detergent. Rinse with clean water using a well-wrung-out chamois leather. Protect the frame with a piece of thin card. Gently brush off built-up grime on stained or leaded glass windows with a clean, soft-bristled brush. If stable, clean the surface with cotton wool just dampened with the same solution.
If a breakage occurs, wrap each broken piece in acid-free tissue, and collect even the smallest shards. Resist any temptation to try to fit the pieces together yourself, as you could damage the crisply snapped edges.
Glass can rarely be mended invisibly, unless a break is at a convenient join between cup and stem, for example. However, synthetic resins with a refractive index similar to that of glass fill cracks and holes effectively. Chips can sometimes be ground out with minimal loss of value. A conservator may also be able to re-create missing pieces such as a decanter stopper or the blue-glass liner of a salt.
Ceramics can be skilfully repaired and then repainted or glazed, that the original damage is almost undetectable. But the restored area may discolour in time, especially if exposed to water, and some glazes – lustre glazes especially – can never be faithfully reproduced. The problem with attempting any repair yourself is that the adhesives which are strong enough to be effective, such as Loctite or Superglue, are not easily reversible, and a more complicated and expensive professional repair may be needed at a later date.
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