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BULB DISCUSSION BOARDS => Antique Bulb Discussion => Topic started by: bungalowboy on February 04, 2018, 02:21:42 pm

Title: Architectural Historical Question
Post by: bungalowboy on February 04, 2018, 02:21:42 pm
Hello all,
Thank you for this forum of gathering information on bulbs. I know very little about bulbs but have recently been researching and discovered this site.
I bought an old house and have discovered that it was designed by a prominent local architect which makes it quite historical. I have also discovered architectural drawings of my home in a collection at the local University which features details of the lighting in the dining room/living room. This drawing was made in the summer of 1911. Upon further research I find that Marvin Pipkin invented the frosted bulb in 1925.
My questions are what would 16 candle power equate to with a modern bulb and how were they frosted back in 1911? I am trying to accurately reproduce this in my home so all the information that you can provide is welcome.

Butch in SLC
Title: Re: Architectural Historical Question
Post by: adam2 on February 09, 2018, 07:03:06 am
The lamps used then would almost certainly have been carbon filament types, 16 candle power was a very common type. They used about 60 watts and gave a very dull yellow/orange light by todays standards.
A modern 60 watt lamp would be much too bright and also much whiter, and nothing like the original.

Carbon filament lamps are still available but are very hard to find. A fleabay search is of very little help since most of the results will be for modern reproductions of early tungsten lamps and not carbon filament.

Most early lamps were available frosted at an extra charge, they were however EXTERNALY frosted and this external frosting tended to attract dirt, dust, grease and finger marks. INTERNAL frosting as is still used today was a later invention.
External frosting was achieved by dipping the bulb in hydrofluoric acid, internal frosting was by filling the bulb with the acid and then emptying and rinsing it before the rest of the manufacturing process.
Inferior external frosting was by coating the bulb with various materials, the heat of operation tended to destroy or remove the coating.

I doubt that you will find a modern carbon filament bulb that is frosted. Carbon filament bulbs are expensive, and hardly anyone wants to pay all that money for a carbon filament and then to hide it behind frosting.

By 1911 it is just possible that very early metal filament bulbs were used, in that case the modern but vintage style filament lamps sold everywhere would be a passable imitation. Frosted ones are rare, reason as above.

Title: Re: Architectural Historical Question
Post by: bungalowboy on February 11, 2018, 10:59:57 am
Thank you for the informative reply, it is all very interesting.

I have some follow-up questions:
So would a 60 watt light bulb of 1911 give about 50% of the light of a modern 60 watt bulb or even less? Half of a 40 watt? What would be your educated guess of an approximation?
Just wondering if I have them on a dimmer what the light emitted would cast to illuminate the room back in 1911.
Title: Re: Architectural Historical Question
Post by: adam2 on February 13, 2018, 06:06:13 pm
A 60 watt carbon filament lamp would give a ROUGHLY similar light output to a modern 25 watt incandescent lamp, the colour would still be wrong though. The modern lamp would be whiter.

An early type of 60 watt metal filament lamp would be broadly similar in output to a modern 40 watt incandescent lamp. The modern lamp would be somewhat whiter, but the difference would be small.

If an approximation of the original lamp type is acceptable, then I would select one of the many modern reproduction vintage lamps that have a squirrel cage metal filament. Expect to pay as little as 2 each

For a closer approximation, select a modern carbon filament lamp of about 60 watts loading, I THINK that Phillips still make these, they certainly did make them until recently and supplies are still available. They are very expensive, I saw one recently on fleabay for over 30.