E6 Colour Developer and plastics

ITD · Feb 9, 2017

Hi

I'm looking at starting to develop E6 using my Jobo CPA-2, and was just looking at the Tetenal kit instructions. I came across the following warning:

Certain plastics absorb traces of the colour developer strongly and permanently.

Consequently, rotary equipment with trays and other parts made of

plastics are not suitable for this process.

I assumed that the Jobo tanks etc would be impervious to photo chemicals but this made me pause and check. Is this a problem with plastic developing tanks (when I did some E6 before I used stainless steel)? Should I dedicate a tank to E6 and keep it away from my B&W process, or is this an issue of contamination between steps in the E6 process?

My reels for the Jobo are all stainless steel Hewes ones so I'm not concerned about those.

Thanks

Paul

AgX · Feb 9, 2017

I never saw this warning. Must be something new.

On their website they even say "optimized for tanks and rotary processors". And I do not know any all-metal rotary tank at all...

Photo Engineer · Feb 9, 2017

Use acid to clean them. No problem.

PE

fdonadio · Feb 9, 2017

Photo Engineer said:
Use acid to clean them. No problem.

Any tips for preferred acid (acetic, citric, sulfuric?) and concentration?

TIA,
Flavio

Photo Engineer · Feb 9, 2017

Can't help OTOMH. Just use it until the plastic stops clearing or the wash water runs clear. I use 35% sulfuric because that is cheap battery acid here.

PE

fdonadio · Feb 10, 2017

Photo Engineer said:
Can't help OTOMH. Just use it until the plastic stops clearing or the wash water runs clear. I use 35% sulfuric because that is cheap battery acid here.

You did help. Thanks!

darkroommike · Feb 10, 2017

Tanks and reels (plastic) will stain. Dedicate a set to just E-6.

Photo Engineer · Feb 10, 2017

Even B&W chemicals will stain plastic over time. My suggestion is to remove any harmful chemistry by using an acid rinse. This also removes stain.

And, if you are worried about E6 chemistry, remember that C41 is quite similar.

PE

Gerald C Koch · Feb 10, 2017

Another reason to use stainless steel reels and tanks.

ITD · Feb 10, 2017

Not sure I want to be messing with sulphuric acid and it's not that easy to get hold of here. Is there something else that would work?

fdonadio · Feb 10, 2017

ITD said:
Not sure I want to be messing with sulphuric acid and it's not that easy to get hold of here. Is there something else that would work?

Don't even think about Hydrofluoric Acid. That will remove the stains, though, before the tank itself dissolves.

Photo Engineer · Feb 10, 2017

ITD said:
Not sure I want to be messing with sulphuric acid and it's not that easy to get hold of here. Is there something else that would work?

I use battery acid which is 37% Sulfuric and you can get it anywhere you have automobiles with acid batteries. You can also use Muriatic acid (Hydrochloric) diluted, or glacial acetic.

I would dilute all of these by about 50% before using.

PE

Anon Ymous · Feb 10, 2017

Ok, let's assume that the reels get stained. Apart from aesthetics are there any other reasons why you'd be worried about it?

Photo Engineer · Feb 10, 2017

Not if you clean them well with a strong acid as noted above.

PE

Rudeofus · Feb 11, 2017

I have made the experience, that corrosive liquids are very difficult and expensive to ship. Therefore you either have a local and reliable source of Sulfuric Acid, or you have to look for alternatives. Here is what I would recommend you look at, if you want to clean stuff with something very acidic:

Ferric Chloride is commonly used to etch the copper layer of printed circuit boards, therefore most electronic parts shops offer it with no hassle. It sounds like a salt, but it's quite acidic. Possible rust stains can be removed with any rust remover including Citric Acid.
Some brands of rust remover: there are different kinds of rust remover, and the MSDS usually tells what their ingredients are. Some rust removers are a combination of Phosphoric Acid and some Phosphonic Acids, and as a result very acidic.
Pool supply pH down powder, typically contains Sodium Bisulfate, which is quite acidic.
Amidosulfonic Acid aka Sulfamic Acid is a popular substitute for Sulfuric Acid and comes in powder form, which is much cheaper to ship, if you have to mail order anyway. It is sold by Silverprint in the UK, and Formulary in the US.
If you are finicky and absolutely insist of getting pure, liquid acids, then Fototechnik Suvatlar ships internationally from Germany. Their price list includes Phosphoric Acid, Hydrochloric Acid and Sulfuric Acid.

ITD · Feb 12, 2017

Rudeofus said:
I have made the experience, that corrosive liquids are very difficult and expensive to ship.

Yes, that was the problem I was encountering. Thanks for the suggestions for alternatives, that's very useful.

ITD · Feb 12, 2017

Anon Ymous said:
Ok, let's assume that the reels get stained. Apart from aesthetics are there any other reasons why you'd be worried about it?

I'm also not completely clear on this question, so I'll put it another way. What would be the effect of not cleaning with the strong acids mentioned, apart from visible staining? Is there a real risk of cross contamination between E6 and B&W for instance, and what would be the effect on negatives? Are these theoretical risks, or do people have experience of ruining their negs in this way for example?

Rudeofus · Feb 12, 2017

I would be very surprised if these stains on plastic had any effect on film processing whatsoever. In order to become active, these stains would have to dissolve in the process liquid, and as we know, they don't dissolve much.

I, personally, have never seen an effect, but I don't run test strips either, and I do use my film tanks for the whole slew of processes. Maybe some experienced lab folks could chime in here?

ITD · Feb 12, 2017

Rudeofus said:
In order to become active, these stains would have to dissolve in the process liquid, and as we know, they don't dissolve much.

I was thinking the same - if it takes strong acid to remove it, how would it suddenly contaminate developer which is alkaline? Mind you, my knowledge of chemistry is minimal!

BMbikerider · Feb 12, 2017

A source of mild acid which is quite cheap in the UK is from the likes of Machine Mart who sell a phosphoric acid based alloy wheel cleaner. It will be edequate even diluted 1-3 to neutralise any left over chemical deposits in the measuring beakers. It will be able to be used several times over. I think it is about £3 for a litre bottle.

Once you get them cleaned, you can always mark the beakers with a permanant marking pen for 1st dev, 2nd dev bleach etc and make sure you use them only for those chemicals. Of course they can be used for plain rinse water without any cleaning.

For mixing the concentrates you could do what I do and use graduated pyrex glass measuring beakers. In UK you could google for laboratory glassware. I use the following company for supplies.

http://www.kingscientific.co.uk/laboratory/laboratory-glassware

BMbikerider · Feb 12, 2017

Rudeofus said:
I would be very surprised if these stains on plastic had any effect on film processing whatsoever. In order to become active, these stains would have to dissolve in the process liquid, and as we know, they don't dissolve much.

I, personally, have never seen an effect, but I don't run test strips either, and I do use my film tanks for the whole slew of processes. Maybe some experienced lab folks could chime in here?

I don't think they mean stains that you can see. I would think more along the lines of chemical residue absorbed into the plastic. I know that one of the chemicals I mix to make up Ektacolour RA4 unless the beaker is not washed out thoroughly, and by that I mean a a couple of minutes under running water, the next time I use that beaker the chemical whatever it is turns slight pink.

Photo Engineer · Feb 12, 2017

The color developing agent will turn pink in water if not removed totally. If this happens, you are not washing well enough and the acid rinse I described earlier is intended to remove color developing agents.

PE

Rudeofus · Feb 13, 2017

BMbikerider said:
I don't think they mean stains that you can see. I would think more along the lines of chemical residue absorbed into the plastic. I know that one of the chemicals I mix to make up Ektacolour RA4 unless the beaker is not washed out thoroughly, and by that I mean a a couple of minutes under running water, the next time I use that beaker the chemical whatever it is turns slight pink.

If you use plastic bottles over and over again (like cheap little me does, BTDT), they start to get visible stains, probably some unhealthy mixture of Sulfur (from old fixer working solution), Silver (from used developer or fixer) and Silver Sulfide (black stain which won't go away in BLIX). Apparently, as you describe, there are compounds which diffuse into the plastic, too, and PE's procedure seems to take care of those.

My conclusion would be that the stains addressed with PE's procedure are well worth addressing (you really, really don't want color developer in E6 FD or in BLIX), whereas the stains I wrote about are usually not that big of a problem, except maybe the yellow Sulfur stains. If you have Sulfur stains, these can be cleaned up nicely by leaving the bottle for a few days in a bath of 100 g/l Sodium Sulfite and 10-20 g/l of some strong alkali like Sodium or Potassium Triphosphate, Hydroxide or Carbonate.

BMbikerider · Feb 13, 2017

I don't use 'cheap' plastic containers. All my chemical holders are glass with the exception of the beakers used in the Jobo processor. It is impossible to get straight sided beakers made of glass so that the fit into the holders on the processor. All the glass beakers I have found have a large circular foot which is wider than the beaker itself and wont fit..

The only way around this is to dedicate one beaker for developer one for bleach and one for fix, and make sure that they are used for those chemicals only.

AgX · Feb 13, 2017

I found them within one minute googling.

E6 Colour Developer and plastics

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