Wetting Agents-can they be used over and over

Mahler_one · Mar 18, 2007

Is there a reason why wetting agents such as Photo-Flo cannot be used over and over again? Inded, can one simply pour the previously prepared diluted working solution back from the developing tank into the storage container for reuse? Obviously there will come a time when the solution has some small bits of debris and grit and will have to be changed, but until then?

Edwin

Photo Engineer · Mar 18, 2007

Yes, it can be used over and over and over. It can get moldy and get suspended particles though. If it gets moldy, throw it away. It should be filtered before use to get rid of the particles.

But, it is so inexpensive, why not just mix fresh?

PE

dancqu · Mar 18, 2007

Mahler_one said:
Is there a reason why wetting agents such as
Photo-Flo cannot be used over and over again? Edwin

The Photo-Flo rinse is a last wash of the film.
Film after film after film after film ...? Dan

patrickjames · Mar 18, 2007

I have never liked Photo-Flo. I have had all sorts of problems with it. I suggest you use Edwal LFN. I simply put a few drops in filtered water and let soak a few minutes. Hang to dry and voila. No muss no fuss.

Patrick

Sparky · Mar 18, 2007

Anybody here using regular dish detergent for this? It's supposed to be an EXCELLENT wetting agent.

vet173 · Mar 18, 2007

Sparky said:
Anybody here using regular dish detergent for this? It's supposed to be an EXCELLENT wetting agent.

one drop per liter. Dont stir in the blender.

Photo Engineer · Mar 18, 2007

Dish detergents contain a colorant and a scent, as well as an oil in some cases to prevent cracking of skin if it is not intended for a dishwasher. They are often alkaline as well to help cut grease.

The oil and the scent can leave an oily residue and the colorant can leave a very slight tint depending on the level used.

So, buy an unscented, clear water white detergent if you must use one.

Also, most detergents are ionic and most wetting agents used in final rinses are non-ionic and totally neutral in pH. Therefore, this also is a reason to avoid them as the sodium salt of the wetting agent can form minute crystals in the coating and change the pH.

But then, I never ever seem to get these points across and people keep using washing detergents.

PE

reub2000 · Mar 18, 2007

Why would you use dish detergent when photoflo is so cheap?

fschifano · Mar 18, 2007

You can, but you'd better be damned careful if you do. Photoflo, and probably any other commercial wetting agent, will pick up some particulate matter over time. I think that a large portion of this particulate matter is a microbial colony because it can be controlled by substituting about 15% of the water with clear rubbing alcohol. But that doesn't account for all the particulate matter and anything that's stuck onto your film and dries into the emulsion will be impossible to remove later.

Sparky · Mar 18, 2007

Photo Engineer said:
Dish detergents contain a colorant and a scent, as well as an oil in some cases to prevent cracking of skin if it is not intended for a dishwasher. They are often alkaline as well to help cut grease.

The oil and the scent can leave an oily residue and the colorant can leave a very slight tint depending on the level used.

So, buy an unscented, clear water white detergent if you must use one.

Also, most detergents are ionic and most wetting agents used in final rinses are non-ionic and totally neutral in pH. Therefore, this also is a reason to avoid them as the sodium salt of the wetting agent can form minute crystals in the coating and change the pH.

But then, I never ever seem to get these points across and people keep using washing detergents.

PE

Not necesarily. If you choose wisely.

The holes I'd poke in that argument are as follows:

1. I think at the dilution they are being used, factors such as municipal water quality are FAR FAR more significant. Think about it. If you wash in a water supply with a pH of 8 (not exactly uncommon), the number of anions aquired from the washing would outstrip the possible number of anions acquired by the wetting agent by a factor a gazillion to one (that number's from empirical research!).

2. Even IF there were a significant increase in pH from the wetting agent - would that not help buffer the paper from acidic attack?

3. The only difference, as far as I know, between a non-ionic and cationic (alkaline) wetting agent, are that the NON-ionic sort have ethylene oxide groups added to the base molecule. This is a petroleum-derived agent. So - if anything, the non-ionic sort add more 'junk' to the emulsion that a good quality dishwashing detergent would.

Sparky · Mar 18, 2007

reub2000 said:
Why would you use dish detergent when photoflo is so cheap?

Why wouldn't you? Actually - a good quality dish detergent is FAR cheaper, when you consider that a vial of photo-flo is about the same cost for 1/200-1/500 the amount of active agent.

Photo Engineer · Mar 18, 2007

Sparky said:
Not necesarily. If you choose wisely.

The holes I'd poke in that argument are as follows:

1. I think at the dilution they are being used, factors such as municipal water quality are FAR FAR more significant. Think about it. If you wash in a water supply with a pH of 8 (not exactly uncommon), the number of anions aquired from the washing would outstrip the possible number of anions acquired by the wetting agent by a factor a gazillion to one (that number's from empirical research!).

2. Even IF there were a significant increase in pH from the wetting agent - would that not help buffer the paper from acidic attack?

3. The only difference, as far as I know, between a non-ionic and cationic (alkaline) wetting agent, are that the NON-ionic sort have ethylene oxide groups added to the base molecule. This is a petroleum-derived agent. So - if anything, the non-ionic sort add more 'junk' to the emulsion that a good quality dishwashing detergent would.

Here are answers in order:

1. In the absence of buffering capacity, the pH of the final rinse dominates. The purpose of the final rinse is to leave no overriding pH effects. Actually, the pH of a photographic material should 'rest' better at the isoelectric point, but that is not essential.

2. Paper uses no surfactant.

3. All surfactants are petrolium derived. Detergents are made from di-nonyl-naphalene sulfonic acid sodium salt which is made from napthalene and other ingredients in a petroleum based synthesis. Common surfactants can be made from natural products as well as from petroleum based syntheses, but at present are petroleum based. Your argument is thereore false.

PE

Photo Engineer · Mar 18, 2007

Sparky said:
Why wouldn't you? Actually - a good quality dish detergent is FAR cheaper, when you consider that a vial of photo-flo is about the same cost for 1/200-1/500 the amount of active agent.

In addition, trace amounts of chemicals affect image stability either for good or ill. Since I have not tested dishwater detergent for image stability in my long experience with image stability tests, I assum you have?

Could you please tell us how these trace amounts of dyes, perfumes and hand oils affect image stability?

Thank you.

PE

reub2000 · Mar 18, 2007

What makes me really scared about this one is that the wetting agent is the last thing used on the film. Nothing will clear the junk off that the dish washing detergent contains. A 16oz bottle of photoflo is pretty cheap, and will last a long time.

jstraw · Mar 18, 2007

Photo Engineer said:
The purpose of the final rinse is to leave no overriding pH effects.

I feel ignorant. I always thought the purpose was the surfactant effect...the sheeting action that prevented the minerals in the water from beading and then drying, leaving spots.

Can you say more about the pH effects? I'm in the dark here.

bdial · Mar 18, 2007

In the case of Photoflo a 16 oz bottle will yield around 400 8 oz batches of working solution for about 8 USD. That will do me for well more than a year. Granted, a drop of dishwashing detergent is more or less free if you borrow it from whatever you are using in the kitchen. But for me, the work I put into buying the film, exposing and processing it is worth much more than the 2 cents worth of tested wetting agent.

Photo Engineer · Mar 18, 2007

jstraw said:
I feel ignorant. I always thought the purpose was the surfactant effect...the sheeting action that prevented the minerals in the water from beading and then drying, leaving spots.

Can you say more about the pH effects? I'm in the dark here.

Sure, photo flo is designed to have no effect whatsoever on the pH of the emulsion, whatever condition you yourself choose to leave it in. This includes alkaline or acidic pH fix solutions.

OTOH, an alkaline detergent, normal for dishwashing forces an alkaline pH whether you desire one or not as it is the last solution used.

I make no judgment, merely point out that pH has an effect on images.

PE

Sparky · Mar 18, 2007

Photo Engineer said:
1. In the absence of buffering capacity, the pH of the final rinse dominates. The purpose of the final rinse is to leave no overriding pH effects. Actually, the pH of a photographic material should 'rest' better at the isoelectric point, but that is not essential.

My point was that there IS no effective increase in pH. There cannot possibly be significant effect on the final rinse solution. Think about it. You add 0.5mL of solution with a pH of, at worst, 7.5 to 20L of rinse water. The increase in pH would be, what... .0001?? I can't think of a better definition of utterly trivial.

Photo Engineer said:
2. Paper uses no surfactant.

I'm not certain whether either - I'm not sure where you're coming from - or perhaps it's not grammatically correct...? Can you explain further?

Photo Engineer said:
3. All surfactants are petrolium derived. Detergents are made from di-nonyl-naphalene sulfonic acid sodium salt which is made from napthalene and other ingredients in a petroleum based synthesis. Common surfactants can be made from natural products as well as from petroleum based syntheses, but at present are petroleum based. Your argument is thereore false.

Not according to this page... but who knows. It could be wrong. That's where I was fact-checking. According to that - it was only the non-ionic solutions which have petroleum additives... I just figure - since we're all acting all insecure about 'additives' (remember your first post on this?) - that would be AN argument NOT to use a non-ionic solution. That's all. Nobody's attacking you, don't worry. I'm just trying to make a case to peopple that many black and white photochemicals are right under our noses... look at those using aspirin for a developer, for example...

Sparky · Mar 18, 2007

reub2000 said:
What makes me really scared about this one is that the wetting agent is the last thing used on the film. Nothing will clear the junk off that the dish washing detergent contains. A 16oz bottle of photoflo is pretty cheap, and will last a long time.

MY point was simply that photo-flo contains more 'junk' than dishwashing detergent does (at least a good quality one).

Photo Engineer · Mar 18, 2007

Sparky;

When processing papers, you do not use a final rinse containing any surfactant.

When washing, there is no buffer capacity to wash water, especially distilled water so the overriding pH of the final rinse dominates. This is neutral in the case of Photo Flo and most other surfactants, but is alkaline for some dish washing fluids.

As for the source (synthesis) of surfactants, I'm an organic chemist with 32 years experience at EK doing this sort of stuff.

PE

Sparky · Mar 18, 2007

Photo Engineer said:
In addition, trace amounts of chemicals affect image stability either for good or ill. Since I have not tested dishwater detergent for image stability in my long experience with image stability tests, I assum you have?

Could you please tell us how these trace amounts of dyes, perfumes and hand oils affect image stability?

Thank you.

PE

Look - I'm sure you're very intelligent and all. But you're engaging in dirty rhetoric (you're putting words in my mouth - I never suggested to use a perfumed, colored dw detergent). I think we've established (several times that we are NOT talking about 'lemon joy' or some such thing. And - may I ask - where on EARTH you're getting the idea of 'hand oils' from?

removed account4 · Mar 18, 2007

i am using a bottle of photo flo ( 8oz ? ) that i bought in 1982.
it is about 1/2 done. i think by the time film is made no longer, i
will still have photo flo left. over rated or not, it takes very little
to do what it is supposed to do, and it is cheeper than dirt.

Sparky · Mar 18, 2007

Okay - well, I guess if you're an organic chemist - then you must know that the word 'buffer' is commonly meant to refer to 'alkali content' - meaning a solution rich enough in anions to resist pH change by the introduction of an acidic solution.

In Los Angeles, where I live - the water is QUITE alkaline. And hence there WOULD be quite a strong 'buffer capacity' as you put it.

When I refer to surfactant - I include the Kodak product "photo flo" in the category. A surfactant is a wetting agent. A wetting agent IS a surfactant. By definition.

So - you say "you do not use a final rinse containing any photo-flo" -

well... who are you to say what I use? I use photo-flo regularly in my final rinse. In the form of a bath.

Photo Engineer said:
Sparky;

When processing papers, you do not use a final rinse containing any surfactant.

When washing, there is no buffer capacity to wash water, especially distilled water so the overriding pH of the final rinse dominates. This is neutral in the case of Photo Flo and most other surfactants, but is alkaline for some dish washing fluids.

As for the source (synthesis) of surfactants, I'm an organic chemist with 32 years experience at EK doing this sort of stuff.

PE

Sparky · Mar 18, 2007

jnanian said:
i am using a bottle of photo flo ( 8oz ? ) that i bought in 1982.
it is about 1/2 done. i think by the time film is made no longer, i
will still have photo flo left. over rated or not, it takes very little
to do what it is supposed to do, and it is cheeper than dirt.

Great. I'm not saying 'don't use photo-flo' - not saying that at all. Just saying that 'in a pinch - you can also use a good dish detergent'.... that's all.

reub2000 · Mar 18, 2007

Sparky: An Anion is particle with a negative charge. An alkaline or base is something that contains hydroxide ions.

Wetting Agents-can they be used over and over

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