Bronze Grave Markers:
Dennis Montagna, Historian at the National Park Service:
For those who have questions on the subject of bronze grave markers and memorials, please contact Mr. Dennis Montagna, Historian at the National Park Service at his email address below to ask questions for one-on-one guidance for their care and restoration:
Statements from Dennis Montagna:
January 27, 2016:
“Most commercially produced bronze plaques for the last 40 or 50 years have a painted surface–usually a brownish background (letters and other high points burnished bright) and then the whole thing gets a clear topcoat.
At some point, the coatings need to be removed and reapplied. Mild gel paint strippers usually work well, although folks who work fast and dirty will uses abrasives.
If you’re just doing a washing, I’d use a very small amount of any of the conservation soaps you’re used to using…Orvus, Igepal, Triton-X…and the apply a cold paste wax that is free of abrasives. Sort of treat it like your car, but don’t use car wax. Use the wax sparingly and buff it out. I like using shoe shine brushes. This may not make a big difference in appearance, but waxes will likely make the lacquer coating last somewhat longer.
From what I’ve seen, some foundries, like Matthews Bronze, apply long-lived coatings. They use a proprietary coating called Diamond Shield, and I don’t know how it should be removed. It might be best to send it back to them for refinishing.
Other producers seem to have less durable coatings, but they may be more easy to remove.
When coatings begin to fail, they usually do it at the edges of things, where it is thinner. Lacquer coatings want to pull away from edges and collect in recesses. Coatings on ground-mounted plaques fail faster because they get beat upon by weather and other things far more than do vertical ones.
If you have a chance to influence placement, always push for vertical! Also, if you can maintain them from the beginning, that’s best, if unlikely.”
January 28, 2016:
“The methods used to produce a bronze plaque are not necessarily ones you would choose to conserve them. Always strive for a light touch.
Just because power grinding and sanding tools were used to make a plaque, it doesn’t mean they’re a good idea in the preservation area.
Aggressive cleaning means loss of surface…just like we see in misguided efforts to clean stone.”