Are early brass lamp reflectors silver or nickel plated?
To my knowledge all of the glass reflectors are (were) silver plated, just as any mirror would be. Good luck with your project, Bill
The reflectors are silver which has a reflectance of about 99% under optimal conditions in the visible spectrum. Nickel has a reflectance of 70% so it is a horrible choice for sending photons down-range.
Bill is correct, silver plated. Nickel and chrome absorb light and are poor choices for a reflector. I realize that statement goes against one's thoughts, because those platings are "shiny", but it's a true statement nonetheless.
Aluminum, silver, and gold are the most reflective of metals, each reflecting over 90% of light transmitted to their surface.
Nickel and chromium are both in the 60% reflective range, which make them very poor coatings for early reflectors.
While we're on this subject, were all acetylene headlamp reflectors glass ? There are metal reflectors in my '13 Jno. Browns, are these likely reproduction replacements ?
The finer points:
Glass vs. metal reflectors
Silvering vs. silver plating
Glass reflectors in early brass lamps are not silver plated. They are silvered using a chemical process called silvering. Has nothing to do with electricity/electroplating.
Metal lamp (brass or steel) reflectors are silver plated (electroplated).
Thank you for these thorough technical responses. I have heard conflicting opinions where some knowledgeable speculate that nickel plate may have been used in some side lamp reflectors (plated metal), supposedly reducing the need for tarnish polishing. Also, among examples that I have over-polished, I do not see a copper surface bleed through, where I understand copper is commonly used for the nickel base.
No surprise that the electroplate job could be expected to eventually fail on a lamp that saw regular use. Unlikely that anyone thought these parts would survive 10 years, let alone 110 years.
Rich: I too would like to know this answer about headlamp reflectors. I have only seen original Corcoran and Victor headlamps that have the glass reflector, but nothing saying this did not change as acetylene lamp technology was on borrowed time in 1913-1914. I will assume there were aggressive attempts to keep this product relevant by its suppliers, where potential cost reductions may have factored into this. I would think that reducing the weight of those lamps alone could have generated an appreciable return.
I've had a hundred carbide headlights over 35 years and picked up and admired a thousand at Hershey over the years. Some very early early headlights had a silver plated brass disk that was basicly part of the lamp. Most of those were self generating, carbide generator made integral with the headlight. For the other 99% they had a glass Mangin mirror that is silver plated on the back. I have never seen an authentic newer carbide light with a plated front Mangin mirror. Cleaning a Mangin mirror, you are cleaning the glass front and not the plated front.