identify your lightbulb > bulb identification key


STEP ???: Un-tipped, Inside Frosted Bulbs
[Bulb is entirely frosted on the inside]

Select the option most resembling your bulb from the drop-down menu to proceed to the next step. Please consult "option descriptions" for detailed info.


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FULL OPTION DESCRIPTIONS / IMAGE GLOSSARY: [Option titles are also linked to proceed to the next step.]

NOTE: To see the filament of an inside frosted lamp, or a soft white lamp, shine a flashlight through the bulb from the back and look for the shadow of the filament.


OPTION A: 540a - (Figures 7, 39 – thumbnails side by side) Bulb is entirely frosted inside, with a smooth surface on the outside of the bulb.  Bulb should have a pearl-like color in appearance.  This is an Inside Frosted Light Bulb, which was introduced in 1925.  Filament is made of either a single or double coiled tungsten filament and mounted as shown in Figures 203f, 204f, or 205f  (i.e., either horizontally or vertically).  Single-coiled inside frosted light bulbs were manufactured starting in 1925.  Double-coiled were introduced in 1935.  If bulb shows two filaments and/or has three different wattages etched on top of bulb, bulb is a three-way inside frosted light bulb introduced in 1933 (see Figure 209t).”  (Go to A37 - Figures 7, 39).




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