I have the following Ilfotol concentrate:

enter image description here

After making a solution (1+200) suggested in the label above, my question is: how much should we use in our final development?

A drop or fill the tank?

And also can we reuse the solution? If so, how long?

  • 2
    \$\begingroup\$ +1 for the question. I can see why it's getting downvoted for lack of research but I'm currently not thinking of a way to ask about the "tribal knowledge" aspect of it. For example, many shooters don't follow these directions...but you wouldn't know that unless you asked, and you wouldn't have asked if you'd simply read the directions...so, yea - I've no idea how to reframe this question or apply it to other solutions in the mix. \$\endgroup\$
    – OnBreak.
    Jul 10, 2019 at 12:59

2 Answers 2


Ilfotol and Photo Flo are recommended solutions to use...but not required to use...in film development. They're effectively really, really dilute soaps.

My bottle of Photo Flo isn't as old as tfb's - it's going on about 8 years - but I can tell you that it still looks the same, smells the same, has the same consistency, and doesn't have any particles in the liquid. So, I assume that it's just fine to continue using.

Its use, for me, is a single drop or two of the concentrate added to the developing tank filled with water and then swished around and then disposed of. If you decide to mix up a working solution, I'd treat it the same. Add what you need to cover your film, agitate, then dispose. When you've run out, make more.

With something like Photo Flo, you want it to be the last thing to touch the film. Using it and then returning it to the bottle could introduce contaminants to the batch (though unlikely). Because the stuff is so cheap and so little is ever used, it simply makes more sense to treat it as one shot.

Side note, I TA'ed my high school film class and, even given our absolute crap budget, still used Photo Flo as one shot. I'd simply mix up gallons of it in the morning and make it available to the class throughout the day, who were instructed in the above technique of cover, agitate, dispose.

  • 3
    \$\begingroup\$ +1. Using a measuring cup set aside with water for your 'final wash' ahead of time allows more effective and gentle mixing of the few drops of concentrate. - Mixing too hard may generate excessive bubbles, which can in turn lead to weird drying spots. - This stuff is stupidly simple to use in general, but has a bunch of easily missed 'gotchas' to use to its best effect. \$\endgroup\$ Jul 10, 2019 at 22:33

FYI, Ilford maintains excellent technical data sheets.

From the third page of this PDF document from Ilford (PDF link), you will find:

Storage and solution life
ILFOTOL concentrate will keep for:-
3 years in full airtight bottles
12 months in half full tightly capped bottles.

Working strength
7 working days.

Note that this is what the manufacturer specifies you should do: this is what is safe and what they will warrant will give good results. In practice many people (me included) simply add a drop or two to the final rinse and then throw it away. The neat solution also lasts far longer than a year in practice. However it is what they will warrant: if you use it like I do then you are on your own.


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