I have a bunch of functional C6 bulbs that are missing their paint.

My older C6 bulbs had a type of flat paint that is semi-transparent when the bulb is lit, you can make out the filament when lit.

My less-old C6's have a typical outside paint, semi-gloss, just like most bulbs from the late 60's-70's.

I can't figure out what kind of paint and painting process was used on these bulbs.

In my experience over the years, most paints (especially the non-transparent kind) do not pass light very well and don't go on evenly. Even the transparent lacquers don't go on smoothly. And C6 bulbs get very hot, every single paint I've ever used wouldn't tolerate the heat of a light bulb.

How did the manufacturers do it back then? I'd love to repaint my bulbs if I could find the right paint. I wouldn't mind buying a small airbrush system to do it.

I'm not altogether sure what they would have used, but there are a few different types of paint that can be used for light bulbs.

I found this one on eBay, the seller is in Germany but you may find something similar locally.

I've found good transparent paint, but have yet to figure out what kind of "flat" paint did they use in the 30's and 40's?

I went looking through my C6 collection, and their is 2 distinct types of paint on the USA made bulbs: flat and semi-gloss.

The flat paint looks very good. The semi-gloss looks kind of like Krylon, I can tell any disparity in thickness of application causes obvious dark spots in the paint.

I've tried searching patents and such, can't find any info. All of the people who made these bulbs are probably dead by now..

All of the people who made these bulbs are probably dead by now..

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