Keep Color Developer away from PETs!

AgX · Apr 27, 2018

Yes, I got no idea how PET beverage bottles entered the photo lab in first place.
(Though their high transparency and low gas permeability are benefits.)

But it would be a good idea anyway to store bottles on a large tray, or modify a cabinet board or such with slats at the edges and cover all with a sheet of PVC.

thuggins · Apr 27, 2018

AgX said:
Yes, I got no idea how PET beverage bottles entered the photo lab in first place.
(Though their high transparency and low gas permeability are benefits.)

That's exactly how PET got into the lab. From first hand experience I've seen that blix is very susceptible to oxidation. Unlike HDPE, PET is virtually impermeable to O2.

It really comes down to the right tool for the right job. As I posted earlier, blix and stabilizer are pretty neutral and will have no problems in PET. Although the first developer is somewhat alkaline, PET appears to work well for it, too. So for the color developer choose a different material, such as HDPE or glass.

lantau · Apr 28, 2018

Working solution for colour negative developers are around pH 10 or slightly higher. When kept at room temp around 20-25 deg the bottles should be fine as in not breaking. Though I do wonder if small amounts of Therphthalic acid will be liberated into the contained solution and if that might affect the developer.

I have a PET bottle here which has been filled with a pH 10 remjet removal solution (carbonate based) for at least a year. It has been slowly used up and refilled one or twice. I see no damage to the bottle.

Higher pH and a hot climate could spell trouble.

thuggins · May 2, 2018

lantau said:
I have a PET bottle here which has been filled with a pH 10 remjet removal solution (carbonate based) for at least a year. It has been slowly used up and refilled one or twice. I see no damage to the bottle.

Higher pH and a hot climate could spell trouble.

Thanks for that info. That indicates keeping the first developer concentrate in PET should be fine.

David Lyga · May 2, 2018

I use Kodak C41 and RA4 developers. (KF 12-1532753 // KP 36-8477184)
I have stressed in the past, that Part C of the RA4 Developer concentrate cannot be kept in PET plastic, as its alkalinity will eat through the plastic and cause leaks and breakage. However, I have no problem with this RA4 developer after it is mixed together. But ... I mix it diluted more than normal, so I cannot speak for 'full strength'.

With C41 there is no storage caveat.

Airtight requirements: With C41, the only part that must be kept airtight is Part C. With RA4, the only part that must be kept airtight is Part B. Both of these 'airtight' components can be kept in PET plastic, filled to the rim. - David Lyga

kfed1984 · May 25, 2023

David Lyga said:
Airtight requirements: With C41, the only part that must be kept airtight is Part C. With RA4, the only part that must be kept airtight is Part B. Both of these 'airtight' components can be kept in PET plastic, filled to the rim. - David Lyga

Part C for C41 is the part containing CD-4 developer?

koraks · May 26, 2023

kfed1984 said:
Part C for C41 is the part containing CD-4 developer?

Yes, at least in the chemistry that David uses/used. There's no universal standard though.

Donald Qualls · May 31, 2023

koraks said:
the chemistry that David uses/used.

Pretty sure that was Flexicolor and Ektacolor. More confident about the C-41, though.

Keep Color Developer away from PETs!

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