jlw
Rangefinder camera pedant
Photo-flo isn't a lubricant -- it's a wetting agent, essentially just a very high-grade detergent. It works by reducing the surface tension of water, so it will flow off the film in a single sheet instead of forming little droplets.
So, undiluted, unused Photo-Flo shouldn't have a limited lifespan -- although I suppose that if you're talking about really old Photo-Flo (e.g. it's still got George Eastman's fingerprints on the bottle) then it might have started to break down. But you should be able to tell by looking if it's working or not -- if it still has that sheeting action, it's okay.
Just to chime in on all the contradictory advice posted so far on the scratching issue, here's something obvious to try: If you're wondering, "Is my film scratched because I'm doing X?" well, STOP doing X and see if it helps. The great thing about washing film, unlike exposing it or developing it, is that you can always do it over!
Here's my take: DON'T squeegee it, wipe it, or touch it in any way. What doesn't touch it can't scratch it. If you still get light-colored mineral streaks even after using Photo-Flo (which can happen even if the Photo-Flo is doing its job) then try this: add some isopropyl alcohol to your final Photo-Flo bath. You don't need much -- the same amount of alcohol as Photo-Flo is plenty, and half as much might do the trick. If that doesn't work, you really need to look at an alternate supply of water.
So, undiluted, unused Photo-Flo shouldn't have a limited lifespan -- although I suppose that if you're talking about really old Photo-Flo (e.g. it's still got George Eastman's fingerprints on the bottle) then it might have started to break down. But you should be able to tell by looking if it's working or not -- if it still has that sheeting action, it's okay.
Just to chime in on all the contradictory advice posted so far on the scratching issue, here's something obvious to try: If you're wondering, "Is my film scratched because I'm doing X?" well, STOP doing X and see if it helps. The great thing about washing film, unlike exposing it or developing it, is that you can always do it over!
Here's my take: DON'T squeegee it, wipe it, or touch it in any way. What doesn't touch it can't scratch it. If you still get light-colored mineral streaks even after using Photo-Flo (which can happen even if the Photo-Flo is doing its job) then try this: add some isopropyl alcohol to your final Photo-Flo bath. You don't need much -- the same amount of alcohol as Photo-Flo is plenty, and half as much might do the trick. If that doesn't work, you really need to look at an alternate supply of water.
