PE and PET bottles and long term oxidation

Radost · Jan 28, 2023

Spoke to a chemical engineer I worked with.
About PE vs PET bottle oxidation.
He said unless leaving the developer a very very long time the difference in oxidation between PE and PET is so little that it would not matter even for chemicals that are a lot more sensitive to oxidation. He said it is inevitable to not leave a little air on top when closing and that air is a lot more than what the PE will let in over double digit years.
Based on that and having a kid who is getting bigger and bigger I will use JOBO PE bottles exclusively And hope for the best.
I was told JOBO bottles are PE but have multiple layers.

gone · Jan 28, 2023

I think your chemist friend is right. Air, light and heat are the real enemies. The old fashioned and easy method is just to drop marbles into your container to keep the level up to the top as you use the chemicals up. Depends on your developer too. I have half filled bottles of F76 Plus that after a year are still as fresh as the day I opened them. When I used D 76 stock solution, nothing would keep that developer from changing activity after 2-3 months, if that.

mshchem · Jan 28, 2023

I've stored the Fujifilm 6 bath E6 chemistry in Jobo bottles, they work great.

halfaman · Jan 29, 2023

I don't know what your friend "very, very long time" is but my chemicals may be stored for years. My choice is standard amber glass as container material, not only considered an oxygen barrier but also inert with many substances and fairly inexpensive. Everything comes out perfect so far, and I have C41 and RA4 developer stored since more than two years.

koraks · Jan 29, 2023

halfaman said:
My choice is standard amber glass as container material, not only considered an oxygen barrier but also inert with many substances and fairly inexpensive.

But it's not squeezable. For this reason, I keep my working stock RA4 developer and blix in PET bottles, but most of the other liquid stuff in glass. Usually plain glass instead of brown as it's easier to see the color of the contents in clear glass. When tucked away in a dark cabinet, there's no functional difference otherwise.

halfaman · Jan 29, 2023

koraks said:
But it's not squeezable. For this reason, I keep my working stock RA4 developer and blix in PET bottles, but most of the other liquid stuff in glass. Usually plain glass instead of brown as it's easier to see the color of the contents in clear glass. When tucked away in a dark cabinet, there's no functional difference otherwise.

I have bottles of several different volumes, from 25ml to 1000ml with a total expense of 30€ (and a couple of expensive 2000ml, volumes for standard bottles end in 1000ml). I transfer the chemicals after each use to the suitable one in order to remain stored in full bottles.

I agree that clear glass is normally enough in a darkroom but the difference between amber and clear standard glass was in the range of cents in most of the volumes.

koraks · Jan 29, 2023

Yeah, I also keep a range of bottle sizes at hand, it's very convenient. And affordable, as you stated.

RalphLambrecht · Jan 29, 2023

Radost said:
Spoke to a chemical engineer I worked with.
About PE vs PET bottle oxidation.
He said unless leaving the developer a very very long time the difference in oxidation between PE and PET is so little that it would not matter even for chemicals that are a lot more sensitive to oxidation. He said it is inevitable to not leave a little air on top when closing and that air is a lot more than what the PE will let in over double digit years.
Based on that and having a kid who is getting bigger and bigger I will use JOBO PE bottles exclusively And hope for the best.
I was told JOBO bottles are PE but have multiple layers.

simple soda bottles have multiple layers to keep the carbonation (fizz) inside but, I'd hesitate to use soda bottles because of the slimchance that they may be mistaken for soda rather than for chemical content by kids or the darkroom worker him or herself.

bernard_L · Jan 29, 2023

Radost said:
He said unless leaving the developer a very very long time the difference in oxidation between PE and PET is so little that it would not matter even for chemicals that are a lot more sensitive to oxidation. He said it is inevitable to not leave a little air on top when closing and that air is a lot more than what the PE will let in over double digit years.

Don't agree with your chemical engineer. See graph below for OTR (oxygen transmission rate)

https://www.tappi.org/content/events/09PLACESY/Course_Papers/frey.pdf

Values are in cc-mil/100in²/day. Non-standard, but convenient units. Such that if you multiply by the barrier area in in², and divide by thickness in mil, you get the permeation in cc/day, standard temperature and pressure.
Now 100in² is a good order of magnitude for the exposed area of a bottle. And 100mil (2.5mm) a generous estimate for the wall thickness.

Reading off the graph the value 150 for HDPE (visual estimate, note log scale), the permeation rate is evaluated as:
150 x cc-mil/100in²/day x 100in² / 100mil = 1.5cc/day
Not exactly negligible over "double digit years".

Also note that the oxygen permeation rate for PET (OPET) is about a factor of 30 down from HDPE; even if PET bottles (soda) are generally thinner than HDPE ones, that remains a significant advantage. Then there is the cap (HDPE / PP) and the gasket (??).

Radost · Jan 29, 2023

how much is cc-mil exactly?

Radost · Jan 29, 2023

Chemicals are shipped in HDPE and last for years.
Including C41 part C

bernard_L · Jan 29, 2023

Radost said:
how much is cc-mil exactly?

It's a unit. The product of a volume unit cc (ciubic centimeter) and a length unit mil (1/1000 inch).
Just like lb-ft is a unit of torque, equal to the product of one pound (force) by one foot (length).

Radost · Jan 29, 2023

bernard_L said:
It's a unit. The product of a volume unit cc (ciubic centimeter) and a length unit mil (1/1000 inch).
Just like lb-ft is a unit of torque, equal to the product of one pound (force) by one foot (length).

It is enough to make a difference

Radost · Jan 29, 2023

bernard_L said:
It's a unit. The product of a volume unit cc (ciubic centimeter) and a length unit mil (1/1000 inch).
Just like lb-ft is a unit of torque, equal to the product of one pound (force) by one foot (length).

MIL - unit of length equal to ¹/₁₀₀₀ inch used especially in measuring thickness (as of plastic films).
Jobo bottles are way thicker than that

koraks · Jan 29, 2023

Radost said:
Chemicals are shipped in HDPE and last for years.
Including C41 part C

I dunno; it doesn't seem to be a hard and fast rule. I've had Fuji C41 and E6 go bad in their original packaging in just a few (2 or so) years.

bernard_L · Jan 29, 2023

Radost said:
MIL - unit of length equal to ¹/₁₀₀₀ inch used especially in measuring thickness (as of plastic films).

That's better than your first reply (edited since)

Radost said:
Jobo bottles are way thicker than that

"that" being one mil... Did you read my post?

bernard_L said:
And 100mil (2.5mm) a generous estimate for the wall thickness.

No real information exchange here.
I quit.

koraks · Jan 29, 2023

Come on @bernard_L, you can't blame someone for a misunderstanding.

Radost · Jan 29, 2023

bernard_L said:
That's better than your first reply (edited since)

"that" being one mil... Did you read my post?

No real information exchange here.
I quit.

Yea I question your information that only PET can hold chemicals away from oxygen long term compared to HDPE “the way chemicals get shipped to you and are good for years”.
“I also had C41 still active in an accordion bottle after almost 2 years mixed and 1 and a half unmixed.
I stoped using them because they are hard to clean.”
I just think the whole issue is overblown out of proportion “especially on this forum” and if there was a benefit using PET or others KODAK will use them and companies like JOBO will find a solution as well.
I just think it has to do more with OCD and meaningful numbers rather than reality.

BobUK · Jan 29, 2023

If plastic is so good why is vintage wine never stored in plastic wine bottles?

A few years back I brewed an all grain Russian Porter, a very strong beer. Kept in crown capped bottles it was still beautiful after three years. I cannot see that happening in plastic storage.

If you find an out of date bottle of fizzy soft drink take note of the reduced hiss as you open it. The gas has escaped slowly and, if gas can travel out it must be able to travel in.

Glass for me.

Radost · Jan 29, 2023

BobUK said:
If plastic is so good why is vintage wine never stored in plastic wine bottles?

A few years back I brewed an all grain Russian Porter, a very strong beer. Kept in crown capped bottles it was still beautiful after three years. I cannot see that happening in plastic storage.

If you find an out of date bottle of fizzy soft drink take note of the reduced hiss as you open it. The gas has escaped slowly and, if gas can travel out it must be able to travel in.

Glass for me.

True. With good caps Glass is king.
But this is about PET vs PE.
And soda bottles are PET. I stopped drinking soda 6 years ago but I have never experienced plastic flatter soda. Always Mexican sprite in glass bottles where I gues caps were not as good

PE and PET bottles and long term oxidation

Radost

gone

mshchem

halfaman

koraks

Moderator

halfaman

koraks

Moderator

RalphLambrecht

bernard_L

Radost

Radost

bernard_L

Radost

Radost

koraks

Moderator

bernard_L

koraks

Moderator

Radost

BobUK

Radost

PE and PET bottles and long term oxidation

Moderator

Moderator

Moderator

Moderator

Privacy & Transparency

Privacy & Transparency