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View Full Version : When does Photo-Flo go bad?



Peter Collins
5-Sep-2018, 07:38
I have 2 containers--size: 1 pint (475ml) each--of Photo-Flo 200 in plastic bottles. Both are about 3/4 full. One is from 2000, the other, 2004. At the rate I use the stuff, I have enough to last a very long time. The bottles stay in a dark closet. Should I be worried about shelf life?

paulbarden
5-Sep-2018, 08:54
I have 2 containers--size: 1 pint (475ml) each--of Photo-Flo 200 in plastic bottles. Both are about 3/4 full. One is from 2000, the other, 2004. At the rate I use the stuff, I have enough to last a very long time. The bottles stay in a dark closet. Should I be worried about shelf life?

I bought a bottle two years ago, and it has an expiration date on the label that states it expires in October of 2018. I don't know what that means in terms of its usability - what DOES happen when it reaches its expiration date?? I've no clue.

photog_ed
5-Sep-2018, 08:56
I have some photo-flo that I've been using for about 50 years, and it was old when I got it. It seems to work fine.

Leigh
5-Sep-2018, 09:23
Photo-Flo is just soap. I see no reason why it would go bad.

Most likely, the expiration date on the modern bottle is just due to some regulation that requies such info on all chemical products. I would not ascribe any validity to it.

- Leigh

Dan O'Farrell
5-Sep-2018, 12:01
Photo-Flo is just soap. I see no reason why it would go bad.

Most likely, the expiration date on the modern bottle is just due to some regulation that requies such info on all chemical products. I would not ascribe any validity to it.

- Leigh

Yes, I agree.

In similar fashion, I've often wondered about the expiry date on sour cream...
what happens to sour cream after the "best before" date?:confused:

Bob Salomon
5-Sep-2018, 12:20
Yes, I agree.

In similar fashion, I've often wondered about the expiry date on sour cream...
what happens to sour cream after the "best before" date?:confused:

Probably the same thing as out of date Twinkees, like maybe 30 years later!

ericantonio
5-Sep-2018, 12:24
In a bottle it's fine. But I had it in 10 gal tanks when I worked in a lab. Eventually some type of scum forms. We added a little isopropyl alchohol to it to keep it clean and to help with drying it seems.

tgtaylor
5-Sep-2018, 13:04
Stock PhotoFlo seems to have an indefinite shelf life but I just learned that a working solution of Tween 20 (Polysorbate 20) doesn't: Last week sludge from using a 5% solution that I originally mixed in 11/15 using distilled water appeared while coating. The stock is an opaque white and I can't see if there is any stringy sludge in it like there is in the working solution. I looked it up on the wen and the shelf life of Polysorbate 20 is one year.

Thomas

Mark Sampson
5-Sep-2018, 13:49
Algae will grow in a Photo-Flo working solution, not in the concentrate. The lab where I worked c.1978 had PF tanks for their b/w sink lines that I changed every Monday morning to avoid this problem.

Pere Casals
5-Sep-2018, 15:39
Photo-Flo is not exactly soap, the active ingredient is "p-tert-octylphenoxy polyethoxyethyl alcohol", a non ionic surfactant. (MSDS sheet)

It also contains Propylene glycol, and water.

Greg
5-Sep-2018, 16:25
Am now using a glass! bottle of Photo-Flo which I bought in 1970 or 1971. Hidden behind other bottles till I did a complete clean up of the darkroom a few years ago.

Peter Collins
5-Sep-2018, 18:45
Wow, Pere, the fact that you could write out that molecule leaves me quite impressed!

Pere Casals
5-Sep-2018, 19:02
Wow, Pere, the fact that you could write out that molecule leaves me quite impressed!

It's quite straight, just google msds with the name of any product

in the safety datasheet of the product you find the ingredients...

Willie
5-Sep-2018, 19:06
When the negative influence of darkroom workers of low character are too close for too long?

tgtaylor
5-Sep-2018, 19:45
Got to thinking this afternoon about how the algae(?) growth got into the Tween 20. Could it be that it became contaminated over time from air that entered while the bottle was open when counting out drops for the sensitizer and/or not flushing out the air in the dropper when capping? The algae or whatever settles to the bottom of the bottle so if I don't shake the bottle as I normally do I could draw from the top and avoid the gunk, But at 3 years is it still good?

Thomas