Church Plate
Church plate is a collective term for church objects made of precious metals. Many parishes still use ancient communion vessels which provide a unique continuity of worship.
Many objects in churches are of precious metals such as gold or silver. However, they may be of varying purity or plated rather than solid. Silver objects collectively referred to as ‘plate' should not be confused with objects plated with silver, where a layer of silver has been applied to a base metal.
As a first step of caring for your church plate you need to identify which items are of historic and/or artistic value and above average monetary worth, and which are of a more modest value. The former group is likely to be used only for special occasions. Such items need appropriate security arrangements and specialist attention for cleaning. Items of more modest value are often suitable for more frequent usage and can be cared for by the informed non-professional.
This guidance note mainly applies to gold and silver items. However, most advice is also valid for other precious metals and alloys.
Causes of damage
The behaviour of metal objects depends on their materials and construction (i.e. whether solid or just a thin layer of metal overlying another) which should be identified by a specialist in order to establish an appropriate care and maintenance regime.
Apart from gold, all metals lose their lustre and darken if they are not kept polished. Silver and gold do not react with water or oxygen at normal temperatures. However, other metals, often present in gold and silver objects as alloys, are affected by a high relative humidity.
Pure gold is immune from corrosion, however, gold alloys with substantial amounts of copper or silver often corrode in the same way and under the same conditions as the alloying metals, only more slowly.
Silver tarnishes, i.e. gradually discolours to brown and black, in the presence of sulphur compounds in the air which originate from the burning of fossil fuels and other industrial activity. The conditions for corrosion are enhanced in a damp environment. Salts and grease in human skin can also corrode silver surfaces and fingerprints can mark a polished surface irreversibly. Crusty green deposits can form where the silver contains a high copper content.
Copper corrodes in the presence of sulphur compounds in the air as well as in the presence of moisture, organic acids, other atmospheric pollutants, salt (in sweat or sea air) or when frequently handled. Typical corrosion products are green crusts or powdery spots.
Pewter, an alloy of tin and lead, is particularly vulnerable to corrosion due to the presence of organic acids, for example in wooden boxes. This is enhanced by a high relative humidity. A patina develops where the pewter object has been left unpolished.
Brass, an alloy of copper and zinc, is sensitive to damp and develops a brown tarnish and green copper corrosion products.
Dust, often containing chemical contaminants, can also hold moisture on metal surfaces and can cause them to corrode, even under appropriate conditions.
Decorative metals, like gold, silver, copper and pewter are relatively soft and easily dented, scratched and abraded. Frequent handling or cleaning can wear away engraving, gilding and silvering, particularly if there is abrasive dust on the surface. Vigorous wiping of the communion vessels can also distort them.
Signs of damage
- candlewax drippings
- dust
- fingermarks
- tarnish
- flaking
- worn lacquer or paint
- fresh scratches
- failing joints or repairs
- loose fixings
- active corrosion: Active corrosion products on iron objects show as orange or red rust, on copper or copper-containing alloys as green spots and on lead, tin and pewter as white eruptions.
Maintenance
Many items are still in regular use and this should be encouraged. However, it is advisable to consult an accredited conservator to identify the most valuable pieces which require special care and should only be cleaned by a specialist in order to keep them in use as long as possible. In addition to silver and gold plate, antique pewter can also be of great value but is often underestimated by parishes.
As the corrosion of gold and silver is normally very slow and wear is cumulative there may be little change in the appearance of church plate between the annual inspections. Therefore, it is advisable to keep longer-term records including photographs which help to identify any changes.
For most metals, the relative humidity can never be too low as moisture causes corrosion. However, the environmental conditions need to be adjusted to suit any organic materials, such as wood or plaster, which are present in many metal objects.
The corrosion risk needs to be reduced by removing sources of gaseous and chemical pollution. Items of lead-containing alloys, including pewter, should not be stored in the vicinity of volatile organic compounds, such as oak, cardboard, MDF or fruit. Silver objects should be kept away from protein-based materials, such as wool, silk or leather, as these contain sulphur compounds which cause tarnishing.
All cleaning methods remove a little of the metal from the surface of the piece and, therefore, the mildest cleaning methods should be chosen. Regular dusting is preferable to frequent polishing as it helps prevent corrosion and too frequent cleaning. A clean, soft, lint-free cloth or a very soft hair brush should be used lightly for dusting, taking care not to scratch the surface. It is a good idea to wear clean gloves when cleaning the object in order to avoid unnecessary fingerprints. Silver items in regular use can be washed in warm water with a few drops of a mild detergent, rinsed with clean water and then dried. It is not necessary to use a silver cleaner on a regular basis.
Traces of old candlewax should never be removed with a sharp implement but with a soft wooden or plastic spatula. Chilling the object makes the wax brittle and easier to remove.
Before cleaning, remove any dust as it can scratch the surface. Light tarnish and fingermarks on silver objects can be removed by gently rubbing with a tarnish-inhibiting cloth for silver. However, tarnish-inhibiting cleaner or polish is not appropriate for items in regular use. Be aware that the surface corrosion of bronze and pewter items results in a highly desirable patina which should not be removed.
There are two methods to remove tarnish or thick layers of corrosion products, chemical and abrasive. Chemical products dissolve the tarnish, however, they are difficult to control, have unexpected side effects, are a threat to health and safety and it is difficult to ensure their complete removal after cleaning. They will not, therefore, be appropriate for communion vessels. Liquid polishes containing powder abrasives are not recommended as the powder can accumulate in cracks and fine detail and attract moisture and encourage corrosion.
Consult an accredited metal conservator for the best cleaning and polishing methods for your specific piece of plate.
Surface coatings such as lacquer or wax may give long-term protection but are not a substitute for regular care and inspections. Also, they are not suitable for all metals and objects. Again, a specialist metal conservator can advise you on the suitability of surface coatings for your metal object.
Plate should be stored in purpose-made cloth bags or wrapped in a soft lint-free cloth or acid-free tissue paper. Pewter should not be stored in wooden boxes but rather in a dry metal cabinet. When closing the safe door, make sure that items are not crushed together.
Church plate is often among the most valuable furnishings in a church and is usually kept in a safe when not needed for worship. It is advisable to ensure that the safe provides sufficient security for your church's valuable objects.
November 2007
Further Information
ICON, Care and Conservation of Silver and Plate
(available on the Conservation Register website)
