Depends on how hard your water supply is, but here where my tap water supply
is hard, I always use de-ionised water plus a very small amount of wetting
agent for the final rinse.  (If I'm doing E6 then I add formalin to the
final rinse as well, followed by heat drying - it helps prevent fungal
problems.)

Alan
    The best way to get rid of watermarks is to gently polish the
non-emulsion (glossy) side of the film with a very clean, (no dust
particles), dry handkerchief. This will get rid of watermarks on the
glossy side but I would be very careful about performing the same
procedure on the emulsion (dull) side of the film.
When you process your next film, wash as usual then when you are
finished washing, add a generous few drops of wetting agent, not washing
up liquid! to the tank. Plunge the spiral up and down in the solution,
remove the film from the spiral and gently squeegee it between your
first and second fingers after ensuring that you have no hard skin on
your fingers. I do this every time and have processed hundreds of films
without problems. Hope this helps.

Ian

You didn't say what format, I have a lot more problem with watermarks in
35mm.  It's the water collected in the sprocket holes.  (Another reason I
love 120 for black and white.)  As a preventative I use distilled water with
a very small amount of Photoflo (or locally available photo-grade rinse
agent).  One poster, (Lloyd?) has suggested spraying film with distilled
water after hanging and another workable suggestion was to hang 35mm
horizontally so that the runoff has less travel distance before it gets out
of the image area (will have to try this if I need to shoot 35mm, and I'm
currently being tempted to buy an old Nikon F, load up some bulk Tri-X and
do the p-j thing just for fun).

Since these are hard water deposits I usually have luck with one of the
following remedies:

Dry polishing--be gentle!

Cleaning--base side only--with straight Photoflo.  For permanence reprocess
after scanning.

Cleaning--base side only--with stop bath.  Most hard water scum is acid
soluble.For permanence reprocess after scanning.

Reprocessing in stop bath, fixer, wash aid and wash, final rinse in
distilled water.  1-2 drops of Photoflo per roll.

This may be one of those cases where processing in a traditional acid
environment--stop bath and hardening traditional fixer is superior to an
alkaline set of chemicals since calcium carbonate and its ilk are more
soluble in acid solutions and less likely to precipitate--comments from the
chemists in the house?

News==----

News==----

Don't use too much wetting-agent for your final rinse. If the stains appear
greasy (which is easy to find out if you try polishing the shiny side
assuming you are talking 35 mm), a short re-rinse should be sufficient to
remove the wetting-agent residue from both sides of the film. Personally the
only stains I've had on the emulsion side so far originiated in the use of
way too much agepon. Just one drop should be sufficient for a half-liter
tank.
I've seen people using undissolved stopping-bath for removing stains that
come form using (hard) tap-water. It works, but I can't help wondering why
you should bother about rinsing your negs if you clean them this way
afterwards.

Apart from using only a small amount of wetting-agent, I shake of most of
the water when the negatives are still in the reel. After hanging the film
to dry, I swipe off the exessive water using a moist piece of leather cloth
that is normally used for cleaning windows (a dictionnary, a dictionnary, my
darkroom for a dictionnary !!!).

Just my experience ...

Philippe

A.    Finding watermarks after processing

The best thing to do is re-rinse them in distilled water and then in
Photo-Flo to which I add not just water but alcohol to improve wetness.

If that does not do it, then there are wetting agents that one can
purchase for direct application on a spot.  I find that they tend to
streak unless, after using them to loosen the emulsion, you then rinse
as noted above.

B.    Prevention

I use Photo-Flo in distilled water with some alcohol added.  As one of
the posters remarked, the problem seems to be most prevalent in 35 mm
film.  With 4x5 and 5x7 sheet film, I hand the film at an angle so that
all water runs to a single low point on the sheet of film.  I hang 35 mm
and 120 film by stainless steel clips, top and bottom, and hope that I
have provided enough distilled water and wetness to prevent such marks.  
Still, I find, that with 35 mm film it is hard to eliminate all
watermarks all the time.

Francis A. Miniter

   Drying marks are usually deposits of magnesium or
calcium carbonate from the wash water. They can usually be
removed by soaking the film is fresh Acetic acid stop bath
for a couple of minutes and swabbing with cotton balls. The
film should then be washed for five minutes and treated in
the following, which is a good general purpose film final
rinse for B&W.

Distilled Water, to make    1.0 liter
Isopropyl alcohol          25.0 ml
Kodak Photo Flo             2.5 ml

Soak the film in this for about 2 minutes and hang up to
dry without squeegeeing.
70% rubbing alcohol can be used, increase the amount to
35ml. Just make sure its alcohol and water, not one of the
flavored varieties.

 If the Acetic acid stop bath does not take the marks off
try Citric acid, it is a sequestering agent for Magnesium
and Calcium. Ilford stop bath is a citric acid stop bath.