Glass doorknobs were first manufactured in the 1860’s in the Boston area. Probably by the Boston and Sandwich glass company. They featured large ferrules (bases) and flat faced round glass knobs. Looking inside there was often a cross design on the reflective surface. These are collectable today.
About 1890 octagonal glass doorknobs were popular. Some of them appear violet to deep purple. After decades in the sun, the element manganese caused this change. After WWI, manganese was no longer used. So this makes dating these doorknobs possible. Oval doorknobs were also used at this time. Rare colors are green, black and amber.
During the depression of the 1930’s fluted 12 point doorknobs were popular. They were made with thick brass ferrules or a thin sheet of brass over iron. Designs varied according to manufacturers. Set screws varied in size as there was no standard. Missing set screws are very difficult to replace today.
If you are purchasing antique glass doorknobs online, there are several caveats.
· Missing set screws as mentioned are difficult to replace
· Designs are different
· Glass may have clouded or show orange rust
· The glass may have separated from the ferrule. (spinning glass knob)
· Set screws may be stuck and not able to be removed
· Spindle threads inside the glass doorknobs may be worn out.
· Iron substructure may have separated from the brass overlay making the glass spin and set screw holes not align in the two layers
· Glass may be chipped or cracked
· Ferrules are badly tarnished.
Purchasing antique glass doorknob hints:
· Try to purchase sets. They will match and probably will be in good shape
· Don’t purchase individual sets as they may have the above problems
· Go through the list above with the seller before purchasing
Restoring glass doorknobs:
· Scrape paint and grime away with a dull knife or wire brush. Do not use a rotary brush as this will scratch the glass.
· Polish the chrome or brass bases with any brass polish. I like to use Cape Cod Polish. It does not leave the white residue behind like others do. A rotary polishing wheel may be used but avoid touching the glass.
· Clean the glass with Windex
Reproduction glass doorknob hints:
· $10 sets are made of zinc or aluminum and will corrode in a short period of time. Lowes and the Home Depot sell these. Many of the problems above listed will occur in a short period of time.
· Good quality doorknobs $45-$125 have solid brass bases and will not corrode
· Available in many finishes
· Doorknobs all match.
· The problems above will not occur
· Use with antique or reproduction mortise locks or reproduction latches made for antique style doorknobs that work with spindles
· Use with rosettes or back plates to support the doorknobs
· Functions can be passage for non-locking doors, privacy for locking doors and dummy for doorknobs that do not need to turn