How Long Does Stock Ethol LPD Last?

[graciemansion]

I ask because I suspect my stock Ethol LPD, which I mixed up in October of 2017, has gone bad. I can't get good blacks with it, even when I mixed up a fresh batch (I generally dilute it 1:4), and it's turned a dark yellow color. I've ruled out everything else (it's at the right temperature), but everywhere I read says it should last "basically forever". Even Ethol's own documentation says it should last "well over a year." I'd already bought a new package and can easily mix it up but before I do I'd thought I'd ask the good people at Photrio, so these are my questions:

1) Does mine sound exhausted, and if not what else could be wrong?
2) How long can I realistically expect stock Ethol LPD to last anyway (well, something more precise than "well over a year")?

 

[NedL]

I think it really does last "basically forever" but only if it's in a well-sealed bottle without much air. I have some here that I mixed in 1/2014 and put into full 750ml bottles. The bottles that are full and sealed are still clear and still develop paper as usual. But one bottle that was only about 1/4 full sat around for a year and it turned a dark yellow-brown color and got weak. ( It changed pretty quickly because I had used it only a couple months before ).

I use it replenished, and over time my "working bottle" turns a similar brown-yellow, but not as dark as what was left in that stock bottle. So I thought it might still work and tried it a couple times, but it didn't. Opened a fresh full bottle and it was still clear and strong as usual. Thanks for reminding me I need to order more. I heard it doesn't come in cans any more.

 

[graciemansion]

Ah, I think that's my problem. It sat around in an only partially filled 1 gallon bottle for at least a few months. Well, live and learn. I guess I should buy one of those accordion bottles?

And yeah, it doesn't come in cans any more. Both times I've bought it it's come in an aluminum packet.

 

[NedL]

Honestly I'm not sure. It usually doesn't take me more than 5 or 6 months to go through one of my 750ml bottles of stock solution, and I don't do anything special during that time. It sits around partially full during the time it takes to use it all. The full bottles are full to the brim and sealed ( actually, they are in a box in a cool dark location -- not sure if that matters. ) That bottle that turned brown was the first time I've seen that happen, life got busy and I hadn't been printing as much as usual for a year or 18 months. I was surprised!

Probably if you keep some of your stock solution in brim-full sealed bottles, then when you open one, the clock starts then. The stuff is amazing, I really love it.

 

[StepheKoontz]

I can say even the undiluted in a sealed bottle (premixed) doesn't last "forever". I had a bottle from about 15-18 years ago, never opened and looked fine. It was totally dead.

 

[MattKing]

I guess I should buy one of those accordion bottles?

Those accordion bottles are not well suited to storing chemicals, even if they are marketed for that purpose. They often allow oxygen in, rarely stay compressed, and are just about impossible to clean properly.
One or more glass or high level PET bottles, each with well sealing caps and filled almost to the brim, are much better solutions.

 

[Renato Tonelli]

I can say even the undiluted in a sealed bottle (premixed) doesn't last "forever". I had a bottle from about 15-18 years ago, never opened and looked fine. It was totally dead.

That’s been my experience as well. I stopped buying it in liquid form unless I know that I will use it up within a month or two.

 

[NedL]

With this much variation in experience, we're probably not accounting for some factor(s) that matter to shelf life. It is interesting that for graciemansion and me, a color change went along with reduced development activity. Apparently not for StepheKoontz and not sure about Renato. Before that recent bottle of mine and reading this thread, I didn't know that anyone had ever experienced stock LPD going bad. I'm not planning to keep mine for 15-18 years to see if it will stay clear and still go bad, but I do have bottles of stock solution here right now that were mixed more than 5 years ago and seem to be perfectly fine.

For what it's worth, here's what I did. I don't know which part is related to storing well for years rather than months. It's possible I won't mention the factor that matters since I don't know what it is.

1. I mixed up the whole can to make stock solution. ( January 2014 )
2. I probably used DH2O, since I usually do when I'm mixing something meant to be stored, but I don't specifically remember that. If not, I used RO-filtered water.
3. I did not boil the water first to help remove dissolved gases.
4. After the powder was completely dissolved, I put the stock solution into 750ml green glass bottles, full to the brim.
5. The green bottles have screw-on metal caps with soft plastic lining, meant to store carbonated water. They seal very well.
6. I clearly labeled each bottle as LPD stock, with the date mixed.
7. I put each green bottle into a black plastic bag.
8. I put all the bottles in a box on the concrete floor of my garage, where it stays cool, padded so that they are unlikely to break in an earthquake.
9. While I'm using a bottle, it is stored in a different box in garage that has a lid ( so no light, still cool )
10. Working solution is in the darkroom, clear PET bottle, not cool; no effort to keep it from light, but not much light in there. It's kept nearly full, maybe 1/2" of air at the top.
11. When I replenish, I take the working solution bottle into the garage and top it off.
12. When I'm done with a bottle of stock solution, I open a new one.

that's all I can think of!

 

[graciemansion]

Those accordion bottles are not well suited to storing chemicals, even if they are marketed for that purpose. They often allow oxygen in, rarely stay compressed, and are just about impossible to clean properly.
One or more glass or high level PET bottles, each with well sealing caps and filled almost to the brim, are much better solutions.

Yes after I wrote that I read some reviews of accordion bottles and they said much the same thing. So I guess multiple smaller bottles are the way to go.

 

[jvo]

for half-full bottles, use argon gas to replace the air... tetanal protectan spray and others.