ECN-2 Chemistry

[Photo Engineer]

I've seen both leuco and leuko in the literature. It is derived from the word for colorless as in white blood cells "lukocytes" and thus your spelling is better than mine, however Kodak publications and our published photographic literature use leuco. So, I did too.

And Roger, why can't photographers follow instructions? Now that is my question to you as I answer to yours.

In this thick film with high temperature and very active developer, it needs to have a stop which acts rapidly and yet will not damage the film. Sulfuric acid is so acidic that it has 2 effects. First it stops, and second, it lowers the pH below the isoelectric point of the gelatin which is about 4.5, or where an Acetic acid stop would be. Thus is decreases swell drastially! There you go! It thus prevents damage to the rapidly moving film in a high speed MP process.

BTW, there is no hardener in the ECN process. The rapid fix hardener is a mix of Sulfuric acid and Alum.


PE

 

[Roger Cole]

I actually didn't ask why one can't use acetic. You may have confused my question with someone else's.

But I did ask about the RF hardener so I guess that is that - get battery acid from HD. I just knew I had the bottles of RF hardener left over. And if the question about not following instructions was WRT using the hardener in rapid fix, I actually do, for my film fix. My paper is most often Ilford who recommends non hardening fix for paper so I follow theirs as well.


Sent from my iPhone using Tapatalk and 100% recycled electrons - because I care.

 

[jsmithphoto1]

I actually didn't ask why one can't use acetic. You may have confused my question with someone else's.

Must've been my question .

 

[Oxleyroad]

Thanks for your info! I was actually thinking battery acid earlier. I've never seen it sold at Home Depot, and I've never looked. Now I am haha. The only place I've purchased it from has been Advance Auto Parts and that was to clean my trays from processing RA-4. Hmmm... thanks! Time to raid the Home Depot! Now I feel like a dummy spelling it leuko ha. I was thinking medical for some reason, I guess. I will have to read my Kodak Minilab manual again. I could've sworn the leuco dyes were formed in the bleach, but I trust you! Wait... it may have been BLIX... Oh well. Thanks again!

I buy all my conc. H2SO4 for my B&w reversal from
http://www.dudadiesel.com/search.php?query=sulfuric

it just arrives in the post...

 

[jsmithphoto1]

Gosh thanks! That's so cool and they are only 2.5hrs from me. Their prices are amazing!

 

[Rudeofus]

I've seen both leuco and leuko in the literature. It is derived from the word for colorless as in white blood cells "lukocytes" and thus your spelling is better than mine, however Kodak publications and our published photographic literature use leuco.

The term 'leuko' or 'leuco' comes from the Greek word 'λευκό', which means white. When this Greek term entered the western world of science, it was originally transcribed to Roman Latin, and this transcription converted the Greek 'kappa' into the letter 'c' ---> 'leuco'. Remember that the letter 'k' is used only sparingly in Roman Latin. Some words were not originally transcribed to Roman Latin first, but to German (which doesn't use the letter 'c' by itself), and in this case the Greek 'kappa' was converted to the letter 'k'. Therefore it depends on the history of each word or phrase using the original Greek term λευκό whether the transcription is written as 'leuko' or 'leuco'.

Now I wonder whether these leuco dyes are white (like milk, as in 'has no absorption in the visible light band, but reflects everything') or colorless (like water, as in 'has no interaction with light at all in the visible light band'). Either way, the Greek word 'λευκό' would mean 'white' as in milk, not 'white' as in water.

 

[Photo Engineer]

Roger, I answered several comments in one post. Sorry I was not clear.

Rudi, coupler dispersions in gelatin look just like milk. I assume the reduced dye would behave similarly. On coating, the dispersions loose their milky nature and become colorless. When you process the film (or paper) the dispersions again become milky and thus the appearance changes based on water content which changes the index of refraction of the product. Thus both appearances apply here.

PE

 

[falotico]

The traditional dye indigo will turn white if it is reduced. In the reduced form it will dissolve in water and this property developed into the process of dyeing with so-called "vat dyes". The white form (or leuco form) was mixed in the vat with the fabric and when the fabric dried the air oxidized the leuco form of indigo back into its blue color. This was the way blue jeans were originally produced.

Not all reduced forms of dyes--leuco forms--are white in color. Neither are dye couplers all white in color. Dr. Wesley Hanson of Kodak noticed that some dye couplers were yellow and hit upon the idea of using them as a mask in color negatives to increase the separation of colors in the final color print. The yellow color filtered out blue light allowing the reds and green to be printed with no interference from blue light.

 

[peoplemerge]

There is a good chance that Flexicolor Bleach III would be within spec for ECN-2.

I'm curious if Flexicolor Bleach III may be used in ECN-2. This could substantially simplify processing for me at least.

If not, I guess the ferricyanide bleach does seem easiest to source... think it's safe to substitute potassium bromide in place of sodium bromide?

 

[Rudeofus]

I have no cost effective access to Flexicolor Bleach III, but mixed bleaches similar to Bleach III myself and got good results. If Ferricyanide bleaches work with ECN-2, then pretty much any bleach formulated with the much weaker Ammonium Ferric PDTA (used in Bleach III) should work.

About Sodium vs, Potassium Bromide: the biggest drawback of Potassium ion in bleach is that it exhausts the process liquid in the following fixer step much earlier. If you put a proper wash cycle between bleach and fixer, then there should be no problem switching between NaBr and KBr.

 

[peoplemerge]

Thanks @Rudeofus! Will try it and report back.

 

[Photo Engineer]

Look guys, there are two types of dyes formed. One is a direct (2 equivalent dye) formed in the CD and the other is a Leuco dye (4 equivalent) which is formed part in the developer and part in the bleach. Only Ferricyanide can properly form the latter, but Iron complexes such as with EDTA dont need to form the former as it is made in the CD. I cannot tell in advance for you which is right, but chances are that if a Ferri bleach is used, then it is needed to form all of the dye and convert all of the silver. Use what is specified and you won't go wrong.

PE

 

[peoplemerge]

Thanks PE!

I'm not a chemist, but a keen learner of science and an even keener direction-follower

TLDR; I guess what threw me is the h2407 (ECN-2) PDF lists 4 choices of bleach, and I naively hoped one of them just happened to be Bleach III. Sure it'll bleach film but not how ECN-2 was designed.

I've just cross-referenced the components in h2407.pdf vs what's on the bottle of flexicolor bleach iii (because a cursory MSDS search didn't show much) and yep, they seem like very different beasts. Ammonium bromide, acetic acid, ferric ammonium PDTA, ammonium nitrate.

#1 is the recommended bleach, "Ammonium “UL” Bleach (SR-33)" - this is referred to as the least expensive UL option.
Followed by 2 "Alternate Process" bleaches, "Ammonium “UL House” Bleach (SR-35)," "Potassium “UL House” Bleach (SB-34)" - this shares tank and replenisher with ECP, which I gather is for developing "print film," when you're ready to projecting that as a movie reel. Dare to dream! Seems like it might also be a nice way to make the occasional transparency.
Followed by 1 "Alternate" bleach, "Ferricyanide Bleach (SR-29)"

The first 3 don't contain ferricyanide, and now that I'm reading more carefully, I understand the UL designates they "can be used by laboratories having to comply with local environmental laws governing the amount of ferricyanide in the process effluent." I read that to mean I'm not constrained as heavily as a high volume lab, but still have to follow legal and ethical disposal, being generally considerate to my neighbors. I'm certainly motivated by lower cost options, at low volume. But other than that, I gather the 4 options should work equally well.

 

[Rudeofus]

@peoplemerge : Kodak's "Recommended Process Bleach" is a mix of Ammonium Ferric PDTA, Ammonium Bromide, Acetic Acid and Ammonium Nitrate, the latter being a mere byproduct from the reaction between Ammonia, Ferric Nitrate and PDTA (called KODAK Chelating Agent No. 1 ion the document). This bleach is very similar in composition to Flexicolor Bleach III. Based on MSDS datas you should be able to arrive at "Recommended Process Bleach" from Bleach III by matching its Ammonium Ferric PDTA content and pH.

PS: the remaining two bleaches labeled "Alternate Process Bleach" are also based on Ammonium Ferric PDTA. It may be easier to match these when coming from Bleach III.

PPS: There is a Ferricyanide bleach labeled "Alternate Bleach", but this is not even the main recommended one. I would therefore conclude that ECN-2 is more than tough enough to handle Bleach III, and that at the same time Ferricyanide is not needed to convert any leuco dyes to real dyes.

 

[lantau]

@peoplemerge : Kodak's "Recommended Process Bleach" is a mix of Ammonium Ferric PDTA, Ammonium Bromide, Acetic Acid and Ammonium Nitrate, the latter being a mere byproduct from the reaction between Ammonia, Ferric Nitrate and PDTA (called KODAK Chelating Agent No. 1 ion the document). This bleach is very similar in composition to Flexicolor Bleach III. Based on MSDS datas you should be able to arrive at "Recommended Process Bleach" from Bleach III by matching its Ammonium Ferric PDTA content and pH.

PS: the remaining two bleaches labeled "Alternate Process Bleach" are also based on Ammonium Ferric PDTA. It may be easier to match these when coming from Bleach III.

PPS: There is a Ferricyanide bleach labeled "Alternate Bleach", but this is not even the main recommended one. I would therefore conclude that ECN-2 is more than tough enough to handle Bleach III, and that at the same time Ferricyanide is not needed to convert any leuco dyes to real dyes.

There is something interesting I once noted in the ECN-2 specs. The document is talking about advantages of using the UL bleach. The advantages over ferricyanide are all technical ones. Cleaner tanks, easier to regenerate etc.

Here is the interesting part. There are advantages of using UL instead of perchlorate bleach, which is not mentioned anywhere else in the document, at least I didn't notice. The interesting item being that UL bleach maintains the same D-min and FILM LOOK of ferricyanide bleach. That would correspond with the post by PE, that bleach can be part of the image determining process. But also that UL bleach is just as good. If Bleach III is so closely related that it behaves the same way, then it'd be ok.

 

[peoplemerge]

Interesting! OK that does seem to line up. I was wondering what Kodak Chelating agent was. The other additive is this Proxel GXL which I gather is an antimicrobial.

 

[trendland]

Umm I'd give you money right now if you had one available?! do you? I was seriously just about to post a thread about this very topic after doing research all week. Can you pm me more info?

The cost of shooting 35mm color negative is killing me right now, I need a bulk alternative. I've already stocked up on b&w, but cine film is the only option left for bulk color negative film

The costs with "bulk" cinefilm and I meant cinefilm in absolute correct condition (not expired - but 3 month not
in use and possible not cooled correctly within this time) can be $ 1,- to 135-36 !

The costs with expired films can be much higher - just look at FPP prices and just
imagine colors from emulsion 1997 expired.
Fine, nice, expansive "Retro" scratch (with some exeptions) !

So if the pricing gets higher and higher
and you should pay more than 10 bucks
to simple C41 negatives - 36 frames nobody should wonder about people
desperately searching alternatives.
Buy the time : Did you know who we should thanks for having Motion Picture Film still today?
IT WAS QUENTIN TARANTINO WHO DECIDED : I SHOULD MAKE SEVERAL TEL. CALLS TO SOME BUDDYS OF MINE !
SO HE CALLED HARRISON FORD AND OTHER ACTORS.THEY FORCED THE BIG STUDIO BOSSES TO GET IN CONTRACT
WITH KODAK AND GUARANTEED A SPECIAL DEMAND TO CINEFILM.
NICE GUYS

with regards

 

[Ian Faisal]

Must've been my question .

I just use Citric Acid for my ECN-2 Stop bath

 

[Photo Engineer]

You should not use citric acid in color processing much less as a substitute for sulfuric acid.

PE

 

[Ian Faisal]

You should not use citric acid in color processing much less as a substitute for sulfuric acid.

PE

what your recommendation? i use 20 gr citric acid for 1 liters water for my ECN-2 Stop bath
what the cause when use citric acid for color development?

how about my Acid Fixer PE? i use Sodium Thiosulfate and Sodium metabhisulfate, its that okey for color development?


Regrads
Ian

 

[Rudeofus]

The last concentrated process liquid in all color processes must have pH around 6.5, therefore your acid fixer is out of spec.

 

[Photo Engineer]

what your recommendation? i use 20 gr citric acid for 1 liters water for my ECN-2 Stop bath
what the cause when use citric acid for color development?

how about my Acid Fixer PE? i use Sodium Thiosulfate and Sodium metabhisulfate, its that okey for color development?


Regrads
Ian

Rudi is correct. Do not use an acid fix for any color process and for some reason that I have forgotten, from my early learning at Kodak, citric acid is not to be used for color products in any way.

PE