Topic: develope regular photo paper as a positive!

[astrobeck]

this has been making the rounds on a few Fb forums, so here it is....
Ethan lives in Albuquerque, so I'm going to try and finagle a little workshop on this soon.
It's very cool!
https://www.youtube.com/watch?v=KZNyqqfPBbs&t=629s&fbclid=IwAR3DqSTpvIzrcQ5950_DaJcpQ0Xsy0HMXWfSE_ZIgkPClezdxeFsvhutXNo

[Francois]

Oh yeah!
I've seen this yesterday.
I didn't know he lived in New Mexico.

I must say it's an interesting process. It was the first time I've seen somebody do a 2 bath bleach process. I know some people mix the acid and the bleach together in some film reversal processes. I'll have to try something like that one day.

[Sandeha Lynch]

Interesting, very.
So I have bought some chemicals.
On their way.
And when the wind cuts down a bit I'll go out and shoot an 8x10.
With a better exposure than last time.
Wet finger held up is not accurate enough.
Not when it's dark.

It's was JvC who pointed me towards piercing decent pinholes.
Way back.
On Photo.Net, when it had decent management.
Though now I buy them in.
It'll be a few days.
At least.

[astrobeck]

He and Joe Van Cleave both live here....
and then there's me..... 

Oh yeah!
I've seen this yesterday.
I didn't know he lived in New Mexico.

I must say it's an interesting process. It was the first time I've seen somebody do a 2 bath bleach process. I know some people mix the acid and the bleach together in some film reversal processes. I'll have to try something like that one day.

[Francois]

After watching the video, the process started bugging me. And like an itch you can't help but scratching, I tried it!
The first test is drying right now and I must say I'm happily surprised.
I had to modify the recipe because the products used are not available here, but it worked just fine. And in the meantime, I discovered quite a few things.

First, you don't need 40 volume hydrogen peroxide. All I could find that was in liquid form was 20 volume peroxide.
When I tried the ½ teaspoon per ½ liter, the tomato dilution like Ethan (cameradactyl) used, it just didn't work.
So I increased the dilution to ¾ teaspoon for ¼ liter and that was enough to get things started. With that dilution, the process went much faster than on Ethan's video. It cleared the paper in only 2 passes.

I also did a bit of research using a chemical reaction calculator.
Citric acid is C₆H₈O₇
Hydrogen Peroxide is H₂O₂

According to the site I used, there is no reaction between both products. So the important part of the reaction happens between the citric acid and the silver compounds. I tried piping this in the site I used but it says it produces an unknown product...

I'm trying to find out what actually happens, but since I'm no chemist all I can do is make-up a theory. My best guess so far is that the peroxide oxidizes the silver particles and the citric acid dissolves the oxidized silver. But since the unexposed silver mostly Silver Chloride or Silver Bromide, it doesn't have any effect on it all.
And the sepia tone that affects the whites is actually a residue from the corrosive process used to bleach out the silver. And since we go from one solution to the other without rinsing, it's the carry-over chemistry that does the work. This explains why it take a few shots to get it right.

[JoeV]

I did a video recently about this process, employing a half-used bottle of 35% peroxide that was over a year old, with good results. I found it best to do the peroxide step with the paper face-down, as otherwise the etched silver that dissolves in solution can redeposit on the surface and block the reaction.

A link to my video: https://youtu.be/vAvGN5euk_Y

Here's a PDF talking a bit about how the process works: http://www.filmlabs.org/docs/citric-hydrogen-peroxide-bleach.pdf

[Francois]

Hi Joe!
Yes, I did watch the video before embarking on the journey.

Thanks for the PDF, I'm going to read it.

[Indofunk]

Great video Joe! Makes me want to try it! (Though I've never shot paper before...)

[Francois]

You should really try it. It's fascinating to watch. I even got my mom to enjoy the process when I had her try it out. Apart from not being very agile with print tongues she really found it mesmerizing.

[Francois]

Here's one of my test prints.
I really should have used a paper cutter to get things straight...

[JoeV]

Another go with the process. I'm doing two rounds of citric acid + H2O2, both face down. There's lots of precipitate coming off the emulsion, I think face up it tends to partially block the action on the silver. After the 2nd development and rinse, I do selenium toning, it improves the highlights, lightens up the gray tones a bit. I'm not using any fixer, I don't think there's much of any silver halide left after the 2nd exposure and development.

This is with the same partially used bottle of 35% H2O2 that I started over a year ago. The paper developer was used, as was the citric acid solution. I'm excited about the results.

This is 5"x4" Arista grade 2 RC paper in semi-matte finish.

~Joe

Owl, Citric Acid + H2O2 Reversal Process, Fujinon 135mm @ F/5.6, 45 second exposure, 4x5 format Arista RC grade 2 paper by Joe Van Cleave, on Flickr

[Francois]

This is getting to be quite interesting.
One of the things that bug me about the process is the dual bath method for bleaching.
I use 20 volume peroxide which is massively cheaper around here and doesn't seem to be any slower than the higher volume one you get. I'm going to try and incorporate the citric acid directly with the peroxide. But first I need to get some rubber balloons to see if it will produce any outgassing that might blow the bottle clean open.... I don't want to make a big mess with the stuff.

[Francois]

Good news!
I tried mixing both the acid and the peroxide in a bottle and put a rubber balloon on the top to see if there was any out gassing and it appears that there is no reaction between both chemicals that might blow the lid off.

Now to see if the mix will work better. It's already getting pretty dark around here so the test exposure will probably take place some other time.

[Francois]

Another update. I tried mixing them last night and the results were definitely underwhelming. Took forever to just half bleach the print.
This is leading me to think that the reaction that bleaches is actually very short lived which explains why we constantly need to replenish the citric acid by alternately dipping from one to the other.

[JoeV]

I just finished modifying my 8x10 sliding box camera for a 24cm, F/4.5 Fujinon Xerox lens, which should be fast enough for seated portraits of a few seconds duration under shaded daylight. Here’s a test image of a ceramic pig planter. Arista RC grade 2, about 3 second exposure under shaded daylight, reversal processed using same chemistry as previous, including selenium toning.

Pig, Citric Acid & Hydrogen Peroxide Reversal Process, 8x10 format by Joe Van Cleave, on Flickr

[JoeV]

Another update. I tried mixing them last night and the results were definitely underwhelming. Took forever to just half bleach the print.
This is leading me to think that the reaction that bleaches is actually very short lived which explains why we constantly need to replenish the citric acid by alternately dipping from one to the other.

The paper I read on the process suggests some ionization happening to the silver oxide in the emulsion by the citric acid bath, that the peroxide reacts to.

[Francois]

Would make some sense.
The acid usually strips out electrons (ok, this is based on a 30 year old chemistry class) from the molecules it reacts with. This would turn the silver into an unstable compound that is easy to oxidize.
So we're essentially submitting the print to a highly accelerated form of aging.
This would also explain the weird color and the blotchiness which are reminiscent of very early photographs.

[Francois]

Last night I was looking at the bottle of citric acid and there was a definite sepia colored sediment at the bottom... I think I'm getting somewhere with my theory.

[Francois]

Just another update on this.
Yesterday I tried dunking into the peroxide first after a quick rinse of the print under the tap.
That was a really bad idea. The print started to fizz like crazy and then the peroxide was just exhausted.

So the first step in the citric acid is a must as it acts as a neutralizing agent and stop bath before oxidizing the silver.