My own empirical evidence shows, after about five years of using the same accordion bottles, that they work.
What is it that makes people have bad things happen to them with the accordion bottles? I see absolutely no difference in the quality of my developers with accordion bottles compared to normal bottles.
Thomas, I too wonder what reasonably scientific tests have been done which shows that accordion bottles do not work. It is said that the plastic of which they are made allows air to get in through the plastic. What is the evidence for this? Looking through old darkroom books they were mentioned as the "things to have" and clearly sold well for many years. You'd have thought that in a very short time, if they were defective, they'd not have sold. Even in pre-internet days when magazines like Amateur Photographer and camera clubs were the darkroom enthusiasts' only source of help you would have expected to see complaints but there doesn't seem to have been any
Plastic "soda pop" type bottles are of course cheaper(no cost at all in fact) but can only be squeezed so far.
When I first set up my darkroom, having bought a set of accordion bottles secondhand, I had never heard of forums such as APUG and did not have the benefit of their content. The accordion bottles looked to be a sensible buy and ignorance being bliss I filled them with stock solution developer and never noticed a problem.
pentaxuser
The problem with accordion bottles is that they are made of polyethylene. This plastic is not impervious to oxygen which sort of defeats their purpose. They should not be used for developers.
Their design makes them impossible to clean should something precipitate on the walls that is not soluble in water.
Another alternative that I've had great luck with is recycled wine boxes. If you and your buddies drink boxed wine it doesn't take too long to get to where you have extras.
I've heard really good things about wine bladders. Friends of mine use them, and keep developers fresh for a very long time.
So how come they work so well, all theory aside?
Some years ago there was a long discussion on pure-silver about storing developers. Of the five most common materials used for bottles glass is the best followed by PET and PVC both rated as good and HDPE and LDPE were rated as poor. In my own experience HDPE and LDPE produced shorter life even with the air queezed out.
Here are some oxygen permeability data from the following website http://www.ucc.ie/fcis/PKplastics.htm
The larger the value the greater the oxygen transfer rate.
LDPE 7900 > HDPE 2900 > PVC 120 > PET 95 (units cm3/m2.24h.atm)
The difference between the two polyethylenes and PET and PVC is striking.
I understand the theory, and I thank you for posting it. What it doesn't explain is why the accordion bottles still work fine.
There are various anecdotal ways the following truism has been said, the exact numbers don't matter, the concept is born out in my experience.
"Perfection is illusive and expensive, every half step toward perfect requires double the effort of the previous step. The first 50% of quality is possible with limited attention and effort, the next 25% takes twice that effort, and so on."
So as a possible example in the case of the accorian bottles the first 50% is available just by putting it in a bottle (any bottle rather than staying in a tray), squeezing out the air may get us to 75% of perfect, keeping it away from heat might get us to 87.5% of perfect.
Theory and evidence go together. Either one absent the other is pretty useless.
there is a theory or, more properly, a hypothesis behind the "if it work, it works" approach. Namely, the implicit assumption, or hypothesis is that it works. Your empirical evidence does not contradict the (implicit) hypothesis and so, you accept your hypothesis as a working theory.
I started with the same hypothesis but, my empirical evidence contradicted the "it works" hypothesis so, I am forced to reject the hypothesis.
This article may be of interest :-
http://www.udmercy.edu/crna/agm/phenvitc.htm
I no longer use accordion/concertina bottles.
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