Are these mirror plates original?

Many pieces retain their original mercury glass plates, identifiable by the characteristic cloudiness and dark foxing spots. These aged surfaces provide the distinct aesthetic that defines antique mirrors. Over the centuries, some plates may have been replaced due to breakage or severe degradation. Examining the edge of the glass and the backing boards helps determine whether the plate dates to the same period as the frame.

How do I hang a heavy overmantel mirror?

Large overmantel mirrors require secure wall fixings anchored directly into masonry or substantial wooden wall studs. Professional installation is strongly recommended due to the considerable weight of timber frames and thick glass plates. Ensure the hanging wire or integrated brackets are rated well above the actual weight of the piece. The mirror should rest partially on a mantelpiece or lower support to distribute the load safely.

What causes the dark spots on the glass?

The dark spots, known as foxing, result from the chemical breakdown of the backing amalgam over decades of exposure to air and moisture. This natural oxidation process creates unique patterns that confirm the age of the glass. Rather than a defect, collectors view this degradation as a mark of authenticity. It distinguishes genuine antique mercury plates from modern reproductions designed to mimic age.