reading the recent posts about photo-flo has me wondering about a few things

i've heard about mixing it weaker than kodak recommends and using distilled water, but never anything about not letting it foam or not letting it sit for longer than 30 seconds…..when i agitate the film in photo-flo i often get foam (not a lot but some obvious bubbles) and at times i've let it sit in the photo-flo for up to several minutes.... are these bad things?

i do have a couple negatives from different rolls that have brown spots on them that dont want to polish off with water, could this be the cause? also once i'm done with the photo-flo soak, i vigorously sling the reel several times to remove liquid and then once i take the film off the reel i "pop" it a few times holding it by the ends, are these safe/normal procedures for getting spot-free negatives?

thanks

joe

-- Joe Holcombe (joe1013_@excite.com), June 26, 2001

Answers

The foam caused by excessive agitation has a tendency to get stuck in the sprocket holes of 35mm film and cause marks when dry. Immersing film for longer than 30 seconds causes exceessive scum buildup, emulsion swelling and will mark the film when dry as well.. As far as flinging and popping the film to remove excess water.Be careful the emulsion is VERY fragile at this point so the less mecanical contact the better. Be carful you don't crease the base as well. BTW I plan on trying LFN as soon as my photoflow is used up. I am a little hesitant to use any wetting agent with alcohol as an ingredient. Many years ago there was a product on the market that proported to dry film instantly. It was basically soapy water & alcohol. It dried the film instantly all right with the most pronounced streaks I have ever seen! What I do is dilute photo flo 50% of recomendation (I dont use distilled water but all the water entering the darkroom is filtered) and gently immerse the film (on the reel) in the graduate I mix the photo flo in. I then gently swirl the graduate around for 30 sec. Then dump the solution, remove the film & hang to air dry. My darkroom has a dust filtration system. RO

-- Robert Orofino (Minotaur1949@iopener.net), June 26, 2001.

I still have the bottle of Photo-Flo I bought in 1984--I use it for cleaning things that I don't want to use strong detergents on, and also as a wetting agent for my brush when I spot prints. But I NEVER use it on my film anymore. I had a plethora of problems with water spots that all disappeared when I switched to LFN. With LFN you only need 2 drops per liter of distilled water to make your film dry spot- free. The first little bottle of LFN I bought lasted almost 10 years. Now I'm on my second bottle.

-- Ed Buffaloe (edb@unblinkingeye.com), June 27, 2001.

Per liter of distilled water add 2.5ml photo-flo (1/2 strength) and 25ml isopropyl alcohol (70% PLAIN rubbing alcohol is OK). Use it one- shot and you'll get no spots or scum. I mix batches smaller than 1l using small medicine bottles with eyedroppers for the alcohol and photo-flo. I insert and remove the reel in the liquid gently to minimize foaming, remove the film from the dripping reel, hang the film up and let the liquid drain off. It's better to minimize wet time of the emulsion regardless of which chemical it's sitting in.

-- Tim Brown (brownt@flash.net), June 27, 2001.

"Slinging" and "popping" the film may be counter-productive. A wetting agent works by allowing the water to flow off as a sheet, rather than breaking up into smaller drops. When you shake off a large amount of the water, the water left on the film will be more likely to break into smaller segments or drops, and will be less likely to flow off of the film without leaving marks.

David Carper ILFORD Technical Service

-- David Carper (david.carper@ilford.com), June 27, 2001.

I use 250 ml of distilled water, add 5 to 6 drops of Kodak photoflo and dip my Minox 8x11 negative strip for about 1 minute. Very clean no water mark, not residue.

Due to the small size of Minox frame, absolute clean is essential, and I found that too much photoflo causes scum on negative.

-- martin tai (martin.tai@capcanada.com), July 06, 2001.