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.