Reply To: Conservation of brass/bronze bookends


Dear Judith
I think the question of coating or protection depends a lot on what will happen to the items and the importance attached to their appearance. If they are being kept in a dry storage container and it was vital that the metal surface can be seen with no distortion of its shine or color, if it was a sculpture for example, and the artist had expressed a view about not coating it, then all the effort would be put into keeping the conditions below 18% relative humidity to prevent further corrosion.
If they were archaeological items and at risk of further corrosion, they would probably be stabilised by immersion overnight in a 3% solution (weight/volume) of benzotriazole in industrial methylated spirits (now called industrial denatured alcohol), allowed to dry (putting them in a dry box for this to remove any traces of moisture from the alcohol is an excellent idea) and then given 3 coats of a 5% solution (weight/vol) Paraloid (Acryloid) B72 in acetone to protect them. Care must be taken not to touch the surface with anything that could scratch it after taking them out of the benzotriazole as the protective layer formed is only a molecule or so thick. Once coated the copper alloy will survive in even less than ideal conditions, although the glove rule and keeping it as dry as possible are both good practice.

Coating with Renaissance wax is a halfway house between the two treatments – it does provide some protection from accidental handling with bare hands and from humidity, but not as much as benzotriazole and Paraloid. It will make it more difficult to apply any other treatment later as the wax will have to be thoroughly removed before other treatments can be applied.

Yes, please advice on storing CDs would be very welcome! Should we start a new post for that?