How Flashbulbs are Made

[Brian Schmidt]

Hello.

Does anybody have an idea how the flashbulbs were sealed without setting them off? Seems like, especially with the AG and similar, that the red hot glass would be so close to the wool that it would just go off. How did they make this work?

Brian

 

[jvo]

good question, hope someone knows... but shouldn't it be "how flash bulbs WERE made?"

 

[DWThomas]

I believe the foil in the bulbs was actually ignited by some sort of oxidizer/metallic compound that was fired by the electrical current though a supporting wire. The compound probably burns at twice the temperature of melting glass, so the foil ribbons would likely not be bothered by the glass fusing if it was done in a typical controlled industrial process.

(All semi-informed speculation, mind you ...)

 

[AgX]

Good question.

Dave is right. The metal does need quite some initial energy to start burning. You can see that in real fires too.
That energy is delivered by a tiny amount of "explosive" splattering around.
(It could be though that the first models indeed were directly ignited but that would necessitate direct contact with that heating wire and also introduced a cooling effect.)

The bulb is not red hot, only the foot part is locally heated. The process is similar to making incandescant lamp bulbs.

But yes, with the AG3 bulb and its even smaller descendants the bulb got really small.

 

[desertrat]

This company still makes flashbulbs. Some interesting information at their site on the current uses of flashbulbs. For some niche applications, they are still the best.

http://www.meggaflash.com/

 

[Brian Schmidt]

Hello.

Seems that there wasn't much of a problem with them going off upon sealing. IanC sent me a link to an article showing their manufacture and they didn't seem to take this into consideration due to the high ign. heat of the primer.

Have a good day,

Brian

 

[tezzasmall]

IanC sent me a link to an article showing their manufacture...

Could either yourself Brian or IanC post the link mentioned, especially if it contains video, as I couldn't find much of interest on a google search.

Thanks.

 

[Ian C]

The article Flashbulbs in the Making by Jack Price in the April 1938 issue of Popular Photography begins on page 24 and then continues on page 86 in the following Google Books file explaining the manufacture of flash bulbs as it was done then.

https://books.google.com/books?id=R...DAS#v=onepage&q=flashbulb manufacture&f=false

If you click onto “View All” you’ll get two links, one to the beginning of the article on page 24, and a second to the conclusion of the article on page 86.

 

[tezzasmall]

Thanks Ian. Going to read it straightaway while it's fresh in my mind to do so.

 

[AgX]

There are severe mistakes in the article, concerning the lacquering and the leakage.
Seemingly the author did not understand the working of the bulb himself.

(The stated inventor is the one of the stated model, but not of the flashbulb as such.)