Cleaning bronze statues is a preventive conservation treatment. This means that it is carried out primarily to slow the natural degradation of an object, in this case a bronze statue, in its particular environment. 

More than any other material used in sculpture, bronze requires cleaning because it is a reactive metal. It is the copper content, within the alloy, that enables the surface to corrode.

cleaning bronze statues

Corrosion doesn’t immediately look shocking or ugly. It begins, as so many things do, by being hardly noticeable at all – perhaps a slight freckling of the surface or run mark, but over time if the statue isn’t cleaned then you will see the surface change in a permanent way. 

The term cleaning is a general one and that can be misleading. There are different ways of cleaning that should all be part of the long term care of a bronze sculpture.

  1. Spot Cleaning is a valuable technique. Bronze statues located inside will need dust removing. Externally, this is more likely to be guano, detritus from trees and insect debris. The technique should be carried out predominantly dry with minimal wet or solvent cleaning. 
  2. A maintenance clean is more thorough, but usually carried out by hand. This involves the removal of all dirt, grease and grime usually using soap solution and a small amount of solvents, followed by the through application of a protective coating.  This mode of cleaning is slower but absolutely essential for the long term care of a bronze sculpture.cleaning bronze statues
  3. The full removal of a coating can also be termed cleaning but does not happen during maintenance cleaning. This often happens during restoration work when a protective coating has failed or a coating has been added, at some point in the statue’s history, to disguise the true condition of a bronze sculpture’s surface.  Methods such as super-heated water or solvent cleaning are used in this mode of cleaning. 
  4. Deep cleaning is carried out when a statue has been left for such a long duration that hand cleaning is no longer viable. Deep cleaning involves super-heated water and removes all guano and dirt residues. This mode of cleaning will strip any existing wax-based protective coatings away, but that is rarely a concern because statues left for years rarely have any protective coating left.                                                                           cleaning bronze statues

Cleaning bronze statues does not mean removing the patina on a statue’s surface. Contrary to what some say on YouTube, it never involves polishing them up so that they are gleaming (with some brasso and elbow grease). It should be about preserving the bronze’s surface, not removing it. 

Cleaning bronze statues should never involve applying acids or alkalis to the surface of a bronze – even if it is natural (no lemons or vinegar!) 

Keeping a bronze statue clean is not just about aesthetics, regularly removing grime, guano and other substances, lowers the rate of breakdown of the bronze’s protective coating.  That means that cleaning bronze statues regularly helps to keep the protection viable for longer. Spot cleaning is essential for removing large particulate matter, maintenance cleaning removes grime and residues that may not be obvious to the naked eye and consolidating the existing protective coating. This combination of cleaning techniques is good for the statue and for a client’s budget because the more robust the coating is, the more stable the bronze will be and that should always be the aim of cleaning bronze statues.