With bent objects, thin section copper-alloy items calm be reshaped
by annealing, but care must be taken not to overheat, as extensive
oxidization will occur and reduce the attractiveness of the object.
More substantial copper-alloy objects are best left as found.
Some copper-alloy items may he improved by enhancing the patina.
A patina might for example be powdery or rough-textured. This can
often be improved by brushing with a typeface brush. If the colour
of the patina is thought to be too light, or perhaps having a patina
of different shades, then the addition of a colored wax can he useful.
Because chemical additives in commercial products can potentially
cause long-term deterioration, they should not he use on important
items. Where their use is appropriate, green, brown or black boot
polish sparingly applied and then brushed in will give a dark glossy
tone. Plain beeswax may also ho used with less drastic coloration.
Conservation lacquers can also be applied for appearance purposes.
When cleaning has left a copper-alloy object looking bright, it
may be thought desirable to restore some form of patina or toning
to it. It is possible to produce convincing green patinas, but this
is a difficult and chemically hazardous process. Other safer methods
rarely produce satisfactory results. The best option if it is felt
necessary to tone down bright metal is to use Tourmaline. With copper-alloys,
degreasing with acid may render objects liable to further deterioration
and so conservation will have to follow.
Many copper-alloy objects will remain stable when excavated, and
Require no particular conservation treatment. The application of
Lacquers as mentioned previously may however aid protection as
Improving the appearance of an object.
One of the most destructive threats to copper-alloy objects is
Known as bronze disease'. This can he recognized by small areas
Green corrosion, which erupts from below the surface of an object.
Caused by the presence of chlorides which were sealed within the
Products. And which can become active if the environment of an
Altered. This may also occur when an object has been subjected
Or electrolytic cleaning. Once it takes hold, bronze disease is
Progressive form of corrosion, which, if left unchecked, can totally
An affected object.
The only solution is the removal of the affected areas. This can
Either by totally stripping an object hack to hare metal, with
Attendant disadvantages. Or by picking out any small spots with
Tool or adapted engraving tool. If any trace of bronze disease
is left, it
To conserve an object, either following the removal of bronze disease
After any form of cleaning and/or toning, treatment with benzotriazole
For short) is now generally recommended. Before using BTA, an object
First be degreased by Immersion in alcohol or acetone, this should
Followed by a prolonged soaking in a solution of caustic soda,
Reduce subsurface chlorides and better prepare an item for treatment.
The next step is to remove the object and allow it to dry, after
Should be placed in a 5% solution of BTA, dissolved in alcohol,
It should be
Left for several days. Then removed and once again allowed to dry
Thoroughly. The final stage is to brush off any loose precipitate
Have formed, and to then apply several coats of a protective lacquer,
Preferably Incralac or another suitable proprietary conservation
Domestic varnishes have additives, which may be harmful in the
long term. The
BTA solution can be used repeatedly, and only needs disposing of
THIS ADVICE WAS KINDLY GIVEN TO US AS GUIDE NOT A GOSPEL METHOD
OF CLEANING, YOU DO SO AT YOU'RE OWN RISK!!!!