Rudeofus Concentrates and Working Solution for E-6 Prebleach Bath Based on Kodak's US5948604A

[Rudeofus]

Rudeofus submitted a new resource:

Rudeofus Concentrates and Working Solution for E-6 Prebleach Bath Based on Kodak's US5948604A - E-6 prebleach formula derived from patent US5948604A

Kodak provided a "teaching patent", i.e. a publication for preservation of knowledge, for their 5 liter E-6 home processing kit. The original patent text can be seen here. While anyone with access to these formulas and ingredients could start mixing and using, this article tries to make these formulas more accessible to amateurs. Please note, that all liquid ingredients except for dilute aqueous solutions and water are given in...

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[ChrisGalway]

Dear Rudeofus, Are you planning to provide similar details for the remaining E6 baths (bleach, fix and rinsing)? Chris

 

[Rudeofus]

Dear Rudeofus, Are you planning to provide similar details for the remaining E6 baths (bleach, fix and rinsing)? Chris

The official formula for bleach provided by Kodak is of little use to us, since it relies on HBr (Hydrobromic Acid) solution. I do plan on posting my own formulas for bleach and fixer at some point. Regarding final rinse: Ron Mowrey (aka PhotoEngineer) posted a decent final rinse formula.

 

[lantau]

The official formula for bleach provided by Kodak is of little use to us, since it relies on HBr (Hydrobromic Acid) solution. I do plan on posting my own formulas for bleach and fixer at some point. Regarding final rinse: Ron Mowrey (aka PhotoEngineer) posted a decent final rinse formula.

Conc. HBr is a stronger acid by pKa, but not really more difficult to handle than conc. HCl. Obviously you need to be able to do that safely. But I don't know what steps in particular are part of that Kodak recipe.

There are no particularly onerous restrictions on the purchase of HBr solution. In Europe, at least. After all you can buy HCl solution as well.

A copy of your ID will be needed for proof of age and that is pretty much it. I can see it at a German dealer I have used a couple of times (S3) and I can see it at a Dutch online shop which I am considering to try out soon. Apparently you can buy up to 100g of KMnO4 as a private individual.

 

[Rudeofus]

Conc. HBr is a stronger acid by pKa, but not really more difficult to handle than conc. HCl. Obviously you need to be able to do that safely. But I don't know what steps in particular are part of that Kodak recipe.

There are no particularly onerous restrictions on the purchase of HBr solution. In Europe, at least. After all you can buy HCl solution as well.

A copy of your ID will be needed for proof of age and that is pretty much it. I can see it at a German dealer I have used a couple of times (S3) and I can see it at a Dutch online shop which I am considering to try out soon. Apparently you can buy up to 100g of KMnO4 as a private individual.

Interesting point, did not expect to buy Hydrobromic Acid with so little hassle. As soon as you get stuff shipped, it becomes more of a hassle, if the compound is an acid/alkali, and yet more hassle, if it's a liquid.

Either way: the formula is in the patent, and the ingredients as listed in that patent will provide chemistry for 1/0.31 = 3 .23 liters of bleach.

For everyone else, who doesn't want to deal with HBr, there are a few simple ways to make bleach, which I have no published as a separate article.

 

[Rudeofus]

Regarding fixer (not sure yet, whether that's worth an article on its own): any neutral rapid fixer will work. Remember, that E-6 creates a high silver load (3*n emulsion layers vs. 1*n layers in B&W film), most E-6 emulsions use highly optimized flat crystals (re: fixing of TMAX films), so it has to be a rapid fixer. Don't use my quick fixer formula (or anything else based on Sodium Thiosulfate) unless you want to use it single shot.

There are ready made fixers for C-41 and E-6 process, and these are typically the cheapest and most suitable fixer concentrates you can find. There are also neutral rapid fixers sold for B&W processing (frequently under the title "odorless"). If the labeling on B&W rapid fixer concentrates won't tell, its MSDS tells you working solution pH. Anything between 6 and 7 will be fine. These ready made fixer concentrates are typically cheaper than any form of Ammonium Thiosulfate you can buy.

If you have access to even cheaper Ammonium Thiosulfate, you can mix Ryuji Suzuki's neutral rapid fixer formula, it's cheap&easy and perfect for color processing. Ron Mowrey's Superfix 1 is also an excellent starting point.

If you want to make a violent thug regardless of cost, try the following formula:

• 600ml tap water
• 200ml Ammonium Thiosulfate
• 50g Ammonium Thiocyanate
• 10 g Sodium Metabisulfite
• 2g DTOD
• Add Ammonia until pH reaches 6.5, then add water to make 1000ml.

 

[MattKing]

If you want to make a violent thug regardless of cost,

@Rudeofus - is "violent thug", perhaps, an example of auto-correct run amok?
If you need help editing it, just ask!

 

[Rudeofus]

@Rudeofus - is "violent thug", perhaps, an example of auto-correct run amok?
If you need help editing it, just ask!

This fixer formula is hideously expensive, but it clears dry Tri-X in less than 30 seconds, and dry Delta 3200 in less than 15 seconds.

Ron warned us, that high levels of thiocyanate can induce reticulation, so this fixer does have some traits of a violent thug IMHO. However, it's always been nothing but sweet&kind&gentle to my film rolls, so it's still in my formula collection.

 

[fert]

亲爱的Rudeofus，关于专利中的漂白配方，它含有硝酸钾，在中国个人无法获得，因为它是危险的受控物质。我想知道是否有其他选择可以替代硝酸钾。

 

[koraks]

Dear Rudeofus, Regarding the bleaching formula in the patent, it contains potassium nitrate, which is not available to individuals in China because it is a dangerous controlled substance. I was wondering if there are any alternatives to potassium nitrate.

It also contains a significant amount of hydrobromic acid. I'd be *very* hesitant to consider handling this in a typical home lab. I'd consider that particular formula for educational purposes and not for home-made use.

 

[Rudeofus]

It also contains a significant amount of hydrobromic acid. I'd be *very* hesitant to consider handling this in a typical home lab. I'd consider that particular formula for educational purposes and not for home-made use.

@fert : The Potassium Nitrate in this formula is there, because bleaches attack stainless steel tanks, and the Potassium Nitrate somehow protects stainless steel. Since most of us work with plastic film tanks, this ingredient is not needed. There were some stainless steel film tanks out there back then, so Kodak had to put it in there.

 

[czygeorge]

I have been using this formula of bleach solution, and I have used hydrobromic acid according to the formula (provided that we use a professional laboratory for protection). This ingredient is mainly to increase bromide ions and lower the PH value. I I personally think that acetic acid and bromide can be used instead, but I didn't do that
I think what is more difficult to understand in this patent is the pre-bleach solution, because it still uses formaldehyde, but all the brands of solutions sold actually use 870-72-4

 

[koraks]

This ingredient is mainly to increase bromide ions and lower the PH value.

I think you're probably right. It also has the advantage of not introducing any unnecessary or unwanted alkali ions, although I doubt that this is very significant.

I think what is more difficult to understand in this patent is the pre-bleach solution, because it still uses formaldehyde, but all the brands of solutions sold actually use 870-72-4

Modern E6 processes don't require a stabilizer step at the end of the process because it's been made part of the pre-bleach bath. So that's why the formaldehyde is there. I guess commercial chemistry doesn't use straight formaldehyde to prevent workers and consumers to be exposed unnecessarily to formaldehyde fumes.

 

[czygeorge]

I think you're probably right. It also has the advantage of not introducing any unnecessary or unwanted alkali ions, although I doubt that this is very significant.



Modern E6 processes don't require a stabilizer step at the end of the process because it's been made part of the pre-bleach bath. So that's why the formaldehyde is there. I guess commercial chemistry doesn't use straight formaldehyde to prevent workers and consumers to be exposed unnecessarily to formaldehyde fumes.

Yes, I agree very much
And am also experimenting with using 870-72-4 for keeping safe. I also suspect that with the use of this ingredient, the large amount of sodium metabisulfite in the original formula is no longer needed

 

[Rudeofus]

Formaldehyde Bisulfite Adduct, which is here mentioned as "870-72-4", will obviously work as replacement for Formalin ;-) The Formalin in the article's recipe will obviously form the same compound together with the Potassium Metabisulfite.

 

[czygeorge]

Formaldehyde Bisulfite Adduct, which is here mentioned as "870-72-4", will obviously work as replacement for Formalin ;-) The Formalin in the article's recipe will obviously form the same compound together with the Potassium Metabisulfite.

Got it!Thanks a lot Rudeo

 

[Josaw98]

Formaldehyde Bisulfite Adduct, which is here mentioned as "870-72-4", will obviously work as replacement for Formalin ;-) The Formalin in the article's recipe will obviously form the same compound together with the Potassium Metabisulfite.

I join the conversation, I am using the pre-bleach proposed by Fuji, it uses few ingredients, here it is:

I did it is by adding the EDTA, then the sulfite, the pH increases so I add a few drops of acetic acid, in a solution Separately (70ml) I add 12g of sodium bisulfite and add Formol drop by drop (10ml) I add this to the mixture of EDTA and sulfite, at the end I add the bleach accelerator. Now from what I read here, perhaps the step you made with bisulfite and Formol is unnecessary.

Also, I only add bisulfite and not sulfite, which I don't like since it raises the pH.


UPDATE

Review this Kodak patent (US 5962604) talks in more detail about pre-bleach, mentions the following:

so I am commenting on an error when using sodium bisulfite

 

[Rudeofus]

so I am commenting on an error when using sodium bisulfite

As you can see, the Fuji bleach recipe has Sodium Sulfite as an ingredient, just about every E-6 bleach formula also has Na2-EDTA as ingredient. Small amounts of sodium salts obviously don't cause problems. What Kodak warns against are prebleaches with "high sodium content". The prebleach formula I derived from Kodak's patent is quite dilute and would therefore definitely not qualify as "high sodium content".

 

[Josaw98]

As you can see, the Fuji bleach recipe has Sodium Sulfite as an ingredient, just about every E-6 bleach formula also has Na2-EDTA as ingredient. Small amounts of sodium salts obviously don't cause problems. What Kodak warns against are prebleaches with "high sodium content". The prebleach formula I derived from Kodak's patent is quite dilute and would therefore definitely not qualify as "high sodium content".

You are right, the concentration is lower, I will try to use the Pre-bleacher that Kodak proposes soon as well.