Black and White Reversal Fail

[Xmas]

Silverprint carries potassium permanganate. They also sell potassium dichromate, but can't supply it via the website. "Potassium Dichromate (We cannot sell Potassium Dichromate on the website, but can supply it with an official purchase order. Please see Note on the Raw Chemicals page)".

Contact them to make such an order. I know some random arts & crafts place will have it too.

I also found it here - http://www.georgeweil.com/ProductDetail.aspx?Menu=1&Level1=75&Level2=1146&PID=4513

http://shop.silverprint.co.uk/Raw-Chemicals/products/461/

Id be in trouble even buying it via a company invoice.

 

[destroya]

There's a perfect substitute for concentrated sulphuric acid.
It's the ph- for swimming pools.
It contains also sodium sulfate which helps in containing the gelatine swell.

this is also what i use. can get a two pound bag at the swimming pool store for under $10. that should last me hundreds of rolls

 

[Truzi]

I don't want to minimize caution with sulfuric acid, but as long as you are careful and use proper safety precautions, you will be fine. It would be a good idea to extend "acid" precautions to all chemicals.

My only exposure so far has been with car batteries, and even at that dilution it can be nasty. I had one leak in my car in high school - the battery tray had rusted away, and as I tried to loosen the seized positive cable bolt (the original repair was supposed to be a new cable), a bolt below the battery punctured it.

As I carried the dripping battery to the side of the garage, I ended up with little holes in my jeans. I waited a couple hours before getting under the car to replace the positive cable at the starter, but some acid was still on the frame - and a few drops landed on my lips and in my mouth! (Obviously I wasn't observing proper precautions). I tell this story to my best friend as she has been learning to do some of her own service lately.

I quickly rolled out from under the car and ran to the kitchen to flush my mouth. My father was outside with me, and since I was a teen at the time, he thought my hasty departure was because I'd heard the phone ring, lol.

The acid tasted of very strong lemon juice. Luckily, no harm was done.

For the purposes of this thread, you will probably be using more concentrated acid. However, you wont' be under a car. Wear gloves and protective clothing (like rubber, nothing that can soak through), eye protection (better yet, also wear a simple shield), and be in a well ventilated area - like outside. Have neutralizing substances nearby as a matter of course (I once had a coworker who kept buckets of water in his home shop just in case something caught fire. Once a hot glue-gun leaked on his hand - rapid relief always nearby).

Chemicals can be dangerous, but safety is easy. Just take your time.

 

[flavio81]

REVERSAL FOR EVERYONE...!

Two years later and i'm re-visiting this topic.

So what i'm looking is for alternatives to the BW REVERSAL BLEACH.
The typical formulas are potassium dichromate + sulfuric acid and potassium permanganate + sulfuric acid.

OK, good if you can find (and i'll try to find) the ingredientes. Potassium permanganate is a controlled substance in my country because it is used for drugs production.

I reason that if a suitable bleach alternative could be found which uses different ingredients, more people would do BW slides.

So now, researching on the web, i found an excellent PDF from Ricardo Leite of Portugal which really blew my mind!!
http://www.filmlabs.org/docs/citric-hydrogen-peroxide-bleach.pdf

The alternative is HYDROGEN PEROXIDE 9% (also known as "30 vol") and Citric acid.
Two easier to find ingredients. In fact Ricardo first tried and succeed using Lemon Juice as a source of citric acid (!) which would make this one of the easiest bleaches to make, ever.
Also Ricardo mentions elsewhere on the internet that he is experimenting using Acetic Acid instead of Citric Acid, which should produce "peracetic acid" when combined with the hydrogen peroxide.

Those two ingredients are easier to get!! Alas, in my country finding 9% h202 is difficult, i mean, some drugstores carry it but only in tiny 120mL bottles, and you find it in 1 of 10 drugstores...
Hair salon supply stores do not have liquid h2o2, they sell it in a cream solution with more stuff added.
And then i've found suppliers of h202 but they sell it on big (20 liter) containers at 30% concentration which is not something to keep easily around the house or manipulate

Alessandro Serrao, who I see has a LOT of posts on reversal bleach formulas, mentioned "Pool Ph minus" as an alternative to sulphuric acid, but i'm not clear what ingredient should "Pool PH-" have to be sure I can use it successfully.

Ok, so an alternative mentioned elsewhere was Copper sulfate + sulfuric acid. But many people say this doesn't work.
Another alternative posted here at APUG by Athiril from Tokio, with sample images that show this actually works was a treatment of Copper sulfate + NaCl (salt) followed with a rinse with ammonia... (!) Another candidate for an "easy" bleach.
(there was a url link here which no longer exists)

However, he does not specify any reversal light exposure, which i find strange. I will ask him/her.

I know that many people will reply "just use permanganate and be happy", but we need alternatives, for not everybody can easily get the products. It's the same as with caffenol -- why bother if D76 is available? Because sometimes you can't get the chemicals you need. Or because you want to use safer chemicals.


PS: I did not take attention to this:

I used to buy permanganate directly from Sigma-Aldrich. A 150g bottle costed me 15€ and it's still half full.
pdeeh: please read the google book I posted on my previous post. You can find in there a new non-rehalogenating bleach using only persulfate and ferric sulfate in an acidic aqueous environment.
PE is right on this (as usual): permanganate is the only viable choice available.

P.S.: the o.p. can contact Sigma Aldrich directly via Peru Química Service SRL Lima, Peru Phone: 51 1 420 2339 Fax: 51 1 420 3660 E-mail: qservice@terra.com.pe

MANY thanks!!

 

[flavio81]

Funnily enough that seems terribly easy to buy - B&Q, RObert Dyas etc will have "drain cleaner" which is a strong solution of Sulfuric

I've surveyed my local hardware / grocery stores and all drain cleaners i've found use one of these:

- muriatic (hydrochloric) acid
- citric acid + phosphoric acid, concentration unspecified
- "organic acids"

Also on pool supplies there is a local "PH minus" product (liquid) whose label say the composition is:
- "acid salts". Is this sodium bisulphate???

and also the same brand sells "PH minus plus PREMIUM" which the label and MSDS say:
- "solution of carboxilic acids" (plural)... is this acetic acid ???

So what is inside those bottles?

As for the substitutes for hydrogen peroxide, i can get "6.5% active oxygen" at pool supplies, this is sodium percarborate which should "release O2" but i am not sure if this could work.

 

[destroya]

REVERSAL FOR EVERYONE...!

...Alessandro Serrao, who I see has a LOT of posts on reversal bleach formulas, mentioned "Pool Ph minus" as an alternative to sulphuric acid, but i'm not clear what ingredient should "Pool PH-" have to be sure I can use it successfully.

MANY thanks!!

here is a quick link the the pool acid I use. 3 years and still on the same 2 pound bag
Dry acid or Sodium bisulfate in granular form

http://www.lesliespool.com/leslies-dry-acid-buckets/dry-acid.htm

 

[Gerald C Koch]

The typical form of Silver Sulfate is Ag2SO4, not AgSO4.. In fact the latter compound is so uncommon, its existence was first Dead Link Removed, and its synthesis involves compounds that no photographer wants anywhere near ...

A bit off topic but silver fluoride also contains the Ag+2 ion as AgF2.

 

[Rudeofus]

@flavio81 : one range of products you should seriously look at are rust removers. Many types consist of a mixture of Phosphoric Acid with phosphonic acids, and the result is a very acidic liquid which will not be harmed by the oxidizer in your bleach. If you can't find anything useful among rust removers, you could also try out Oxalic Acid or Sulfamic Acid. Both are cheap and very acidic, come in solid form, and will not form extremely insoluble silver salts.

When you use peroxides to bleach your film, be careful that your emulsion doesn't come off. Some years ago I experimented with peroxide bleaches (there are many patents about this), and even small amounts of peroxide would instantly kill my sample film. YMMV

@Gerald C Koch : Congratulations, you found an ionic compound where I wouldn't want to be anywhere near the cation AND the anion

 

[Europan]

I once used peroxide to bleach and the film was blank afterwards, coating gone.
Very tricky because the oxigen compounds with the silver salts but the hydrogen ions dissect the water to form H2 and water. The water bubbles, you have like boiling water in the emulsion!

 

[Athiril]

Citric acid can work, but the ending results are sub-par and it takes a lot of time and work.

I did permanganate and citric acid, it took about 40min+ of bleaching, with two changes of bleach. The citric acid seems to have slow/weak anti-oxidant properties and weakens the permanganate subsantially, but it slowly works, it does help it prevent damage to the film, but the results werent as good as other bleaches, though it did work mostly.

I've tried 3% H2O2 before as well I think without much success.



There is one other candidate that I think might work well, but I haven't tried, it is Iron (III) Oxide and sulphuric acid or sodium bisulphate.

I prefer to use dichromate based bleach for any serious reversal, as it is reliable, and flexible, and wont damage the film.

 

[flavio81]

Citric acid can work, but the ending results are sub-par and it takes a lot of time and work.

I did permanganate and citric acid, it took about 40min+ of bleaching,

Hi Athiril! Please take a look at my reply on your thread regarding bleach using copper sulphate.

You mention you tried citric acid + permanganate. My post was regarding the combination of citric acid + hydrogen peroxide which is what Ricardo Leite used on the PDF above.

Again, i agree that the "gold standard" for this is potassium dichromate + sulfuric acid, but I think that for the sake of the future of analog photography we should research easier, healthier alternatives further. This will open up doors to people who otherwise could not try the reversal process because of unavailability of specific chemicals.