Dud flashbulbs?

[Moopheus]

The first time I tried to use flash bulbs with my Speed Graphic, one of the bulbs blew to pieces (little glass shards everywhere). So it was decided that I wouldn't try that again without some sort of shield. I've managed to rig something up with a clip-on diffuser and some extra plastic I had from another project. I shot a few sheets of Fuji instant film to check the exposure with the diffuser.

I used seven bulbs while testing. Three of the them were duds, and one fired on the second try. Now, I'm not entirely surprised by the occasional dud with 30+ year old bulbs, but I was wondering if there was a way to tell if a bulb was going to be a dud. I examined the bulbs that did not fire, and it seemed that on two there was a visible bit of what appeared to be corrosion on the base, but one appeared to be clean.

Also, since one fired on the second try, I have to ask if there is a good way to make sure that the contact in the flash handle is good, or to make sure it is clean.

 

[Photo Engineer]

Flashbulbs of that era were coated with a thermoplastic to guard against shattering. The bulbs would form blisters on the surface from the plastic but would not shatter. So, either the plastic has degraded, there is none, or these are very low quality bulbs.

I always burnished the contact on the bulb on my pants before I put it into the holder. Some people I knew, spit on them as well.

PE

 

[railwayman3]

Sorry if it's obvious, but did you check any safety spot in the bulbs, perhaps on the inside of the glass or on the centre wires? This should be blue, if it's pink, air has leaked in and the bulb will likely fail or or break.

I've experimented with some of smaller flashbulbs and flashcubes, bought on Ebay, which, from the packets, must have been from the 60's or
70's and don't recall any failures when the safety spot was still blue.

 

[Anscojohn]

The first time I tried to use flash bulbs with my Speed Graphic, one of the bulbs blew to pieces (little glass shards everywhere). So it was decided that I wouldn't try that again without some sort of shield. I've managed to rig something up with a clip-on diffuser and some extra plastic I had from another project. I shot a few sheets of Fuji instant film to check the exposure with the diffuser.

I used seven bulbs while testing. Three of the them were duds, and one fired on the second try. Now, I'm not entirely surprised by the occasional dud with 30+ year old bulbs, but I was wondering if there was a way to tell if a bulb was going to be a dud. I examined the bulbs that did not fire, and it seemed that on two there was a visible bit of what appeared to be corrosion on the base, but one appeared to be clean.

Also, since one fired on the second try, I have to ask if there is a good way to make sure that the contact in the flash handle is good, or to make sure it is clean.

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Clean the contact in the gun with a type writer eraser. Polish the anode?--the nubbin sticking out the end of the bulb with something more agressive to clean up the oxidation. Try the striker on a pack of matches. Crocus cloth; even an emery board (lightly).
In ye oldene dayz, we used to lick the bulb before putting it in the gun. Not the best idea, perhaps; but it looked, oh so, pro.

 

[Sirius Glass]

Flashbulbs of that era were coated with a thermoplastic to guard against shattering. The bulbs would form blisters on the surface from the plastic but would not shatter. So, either the plastic has degraded, there is none, or these are very low quality bulbs.

I always burnished the contact on the bulb on my pants before I put it into the holder. Some people I knew, spit on them as well.

PE

I burnished the bottom and spit.

Look for the blue spot.

Check the coating.

Clean the contacts with an eraser as AnscoJohn said.

Check the batteries.

Steve

 

[BrianShaw]

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Clean the contact in the gun with a type writer eraser.

What's a typewriter?

 

[DWThomas]

NOTE: It may not apply to ancient flash guns, but in today's electronic equipment, many contacts are plated with a very thin coating, sometimes gold, thickness measured in microinches. These should never be cleaned with erasers as it damages the plating. Much better to use a cotton swab or cloth dampened with alcohol.