Example - cleaning gilt bronze sconces

Louis XV Style Sconces by Maison Millet
Image 1 - One of a Pair of Millet Sconces
One Saturday in Spring 2023, I happened upon one of those rare but happy bargains at Marche' Vanves. While looking at some brocante, I notice a pair of blackened bronze sconces. Closer scrutiny revealed: * The quality of the casting was very good * They were not identical, each had slight variations from the other (as sign of higher quality) * They were post 1900 (made for electricty) * Closer examination showed they bore the stamp of Maison Millet, one of the best bronze makers of the late 19th century. The question, of course, was could they be cleaned? A pair of sconces that permanently look like I bought them fresh from a house fire are of limited value. I would like to pass on how I decided they could be cleaned or at least determined that they were low risk. Unfortunately, the visual cues are difficult to describe as their are a number of exeptions to every rule. 1. Lack of evidence of prior cleaning - this is the easiest thing to spot on a bronze. Image 2 below illustrates classic overcleaning on a Regence-style commode mount. The gilding has been removed from every raised surface but is bright in the crevices. There is no repair for this other than regilding.
Image 2 - Rubbed Bronze with Gilding Removed
Maison Millet specialized in the production of furniture and decorative objects of very high quality in the Louis XV and Louis XVI styles. At the end of the nineteenth century, Millet also produced art bronzes.
The reputation of this house is validated by its medals at universal exhibitions as well as the reproduction of emblematic furniture such as Queen Marie-Antoinette's jewelry case.Maison Millet stamped "MILLET" on the wood of the furniture or engraved "Millet à Paris" on the edge of the locks and bronzes. The house also often uses Alfred Schmidt Paris locks, signed inside.Highlights of Millet's history1853: Creation of the workshop by Blaise Millet, at 11 rue Jacques-Coeur in Paris (then 23 bvd Beaumarchais)1889: Gold medal at the Universal Exhibition of Paris1900: Grand Prix at the Universal Exhibition of 19001890: Théodore Millet, son of Blaise, takes over the management and ensures a strong development1918: End of activity From: www.meubliz.com
2. Image 2 illustrates another bad sign - a flat Hersey brown color. This is the base color of aged bronze and it is an indication that there is no gilding remaining. Similarly, a verigris color also means there is no gilding to clean.
3. Image 3 below shows the bronze patina on the Millet Sconces with an excellent potential for cleaning. The patina is uniform with no gross variation. Note that it is clearly dirty, but a subtle gleam is present in many areas. Observing the sconces from the top and bottom, the bronze is clearly dirtier on the top. This is 100 years of accumulated dust and cigarette smoke. This dirt can all be removed with bolling water, soap and a soft brush.
Image 3 - Dirty, but Hidden Gold
Image 4 - More work to do, but truly night and day!
Just so you have no wrong ideas, it took five soaks and about four total hours of cleaning with a soft brush to achieve the level of shine shown by the sconce on the right. Hard work but worth it. I love the contrast shown in the close-up of the cleaned bobeche below. Note what you see is gilding, not polished bronze.