HOW TO CLEAN A BRONZE SCULPTURE
Recently, we had an enquiry from the archivist at Pembroke College, Oxford – Amanda Ingram.
The college had rather a splendid bronze bust which had, unfortunately, been languishing in a basement for some time. It was to be relocated to a prominent position in the college but it had to be cleaned and Amanda came to us for advice.
She said, “I have given it a light wipe with distilled water to remove surface dust but there is quite a lot of it which has a kind of fine crust on the surface. It is as if someone has wiped it with a dirty rag (for example containing paint residue) and this has set on the surface. The other thing is that it looks like parcel tape or something has, at some point, been stuck on his face and has, likewise, left a hard adhesive residue.”
Our first suggestion was to try a solvent like acetone to remove the parcel tape residue and this worked extremely effectively. The rest that follows relates only to the dirt. Regarding the wiped, crusty areas we recommended trying to clean it first with some soap and water and if it worked to apply a couple of coats of micro-crystalline wax to the surface for protection. We advised trying a small patch first and look at the outcome before going too far.
Amanda asked, “is nail varnish remover a suitable acetone or does it need to be a purer version? And, what sort of soap is best to use?”
Our advice was to buy a pure acetone as nail varnish remover often has added components. Although neutral soap solution is always a safe bet, it can be less effective at cleaning stubborn dirt and require more rubbing at the bronze’s surface which isn’t a good idea. Diluted Vulpex soap is slightly alkaline, but providing it is properly removed, can be a gentler method.
Amanda returned a short while later reporting that unfortunately, the dirt was still stubbornly in place.
Our advice was to try a little abrasion with something very fine. Just to do a very small area at the start with something like a very fine bronze wool and that this could be used with a little soap solution.
Amanda’s results speak for themselves. She applied Renaissance Micro-Crystalline wax after for the statue’s protection. Her careful approach has yielded some great results. Well done, Amanda!