Propylene Glycol Anti-Freeze Gone Bad?

[MichaelMadio]

I was mixing a new batch of PC-Glycol and ran into a strange issue. I use pet safe anti-freeze (Prestone Low Tox) which has been working well for years. As I was stirring the mixture, I noticed bubbles forming and in a few minutes there was a bunch of foam at the top. The bubbles and foam eventually went away so I thought nothing of it. I processed a roll using my fresh batch of "interesting" PC-Glycol only to find it was completely dead. Negatives were completely blank, no edge markings, nothing. The anti-freeze was about 1/4 full and has been around for quite some time (at least a year, probably more). I know I should be using proper propylene glycol but sourcing it in Canada in relatively small non-industrial quantities is a challenge. Does propylene glycol anti-freeze go bad? Has this happened to anyone else?

 

[Rick A]

I guess that it does eventually oxidize.

 

[Gerald C Koch]

There is a problem with using antifreeze. You really don't know what's in it. Manufacturers can make changes without any indication on the label as to what the changes are. Buy some pure propylene glycol from a chemical supplier and try again.

Propylene glycol does not go bad and it does not oxidize. This is a case where you really need to keep a darkroom notebook and record what you have done. Did you forget to add an ingredient? There is no way of telling without a notebook record.

 

[Alan Johnson]

www.shamrockchicago.com/PrestLTAFSpec.html
It contains 1.8% soluble inhibitors.One of them might act as a restainer like Benzotriazole. But this is just a theory.

 

[Nicholas Lindan]

Propylene glycol is very stable and won't oxidize.

However, anti-freeze isn't just Prop. Glycol - the stuff also contains corrosion inhibitors and may contain ingredients to preserve water pump seals and bearings along with coloring and bittering agents. As Alan suggested, it is likely the corrosion inhibitors were overly inhibitive.

There is no guarantee the additives will be the same from batch to batch as products are always improving/getting worse/getting cost reduced/having features added.

 

[MichaelMadio]

It turns out I didn't look hard enough when trying to find propylene glycol. I just found out I can get it from the local pharmacy. I wish I had known sooner ... oh well.

 

[mgb74]

Prop Glycol based anti freeze will almost certainly (i.e. bet my Hasselblad against your Holga ) contain ingredients for lubricating the water pump among other things.

If too expensive from the pharmacy, check dairy farm supply stores. It's used for medicating cows. May not be lab grade, but 100% PG. For example: Dead Link Removed

I would do a search for "Propylene Glycol U.S.P.".

 

[mrosenlof]

I realize this thread is rather old, but mixing up phenidone and vitamin C in antifreeze last night, like the OP, I had a bunch of bubbles that eventually cleared and the powders were disolved. I was using a heated magnetic stirrer, a great device for this stuff if you happen upon a cheap one like I did.

Did the usual mix with 5g/liter of sodium carbonate and everything was just fine.

Sierra brand antifreeze. New. The Glycol solution was green. Turned orange when mixed with the carbonate solution, maybe the antifreeze has some indicator?? It poured out of the tank mostly clear after developing. But the negs were fine. Fp4+ 35mm.

Any chance you forgot the sodium carbonate (or whatever you use to raise pH?) that would lead to little developer activity.

 

[MichaelMadio]

No, I didn't forget the alkali. Interestingly, I found an old bottle of PC-Glycol mixed from the same container of anti-freeze and it worked fine. I think it was the relatively large volume of air in the 1/4 full container that caused something to go wrong, maybe excess moisture, don't know.