I finally discovered (at least partial) solution to my problem. Don't know what mechanism makes it, but potassium metabisulphite wash was the reason which caused paper base colouring after process.
At first it was pretty confusing because as a wash it seems to work perfectly and totally removes all stains after permanganate bleach, leaving paper totally bright white. But as I told before, very unpleasant yellow tint will then appear after final development and fix.
Some years ago I used weak sodium hydroxide dilution as a wash, so I swapped back to it and got rid of colouration. What I stated confusing was that sodium hydroxide wash doesn't solve permanganate stains totally and will let paper pretty dirty looking, but this will be compensated in final developing which cleans it again. After fix and wash it stays clean and neutral too.
If someone is wondering why I am using this paper reversal process instead of traditional negative-positive method, this is the reason:
Nice new Cabinet Cards.
Great work!
Tin Can
So you are doing this with a portable darkroom? Sort of a no-mess version of wet plate?If someone is wondering why I am using this paper reversal process instead of traditional negative-positive method, this is the reason:
Hello,
after some test I concluded that 1.5 cand give me rather better results than 3 ISO.
Also, after seeing some other recipes for the bleach, I decided to use 2 minutes instead of one (If you wish, I will share the test image that I made to conclude that)
This was the first test with 3 ISO (use exactly the recipe used suggested here)
The last image with 1.5ISO
The reason for going down one stop is related with the fact that all images came a bit to dark (so the paper needed to be burned a bit more in the first exposure)
Actually it is pretty much like no-mess version of wet plate. I have had this museum project going on for several years and this is a perfect process for it; it's fast (with RC paper it can be done dry-to-dry and even mounted on cardboard within 20 minutes under primitive outdoor museum conditions), still it's a traditional silver based process.
Orthochromatic BW paper tonal range is pretty close to wet plate and any impurities of process just makes more old look to it. And maybe the best of all, final developing can be done on daylight, so everyone standing around my desk are able to see the magic of image appearing on paper...
Darkroom with safelight is only needed for the first developing/bleach/clear steps and also for loading plateholder, so it can be done in quite small or even portable darkroom.
I am just starting out with paper negatives, getting interested in positives.
I see permanganate bleach mentioned in this thread, and I see very nice photos on Flickr by dipositif who uses potassium dichromate with sulfuric acid as bleach. I am collecting tools for Bromoil, and so already have copper sulfate, potassium bromide, and potassium dichromate on hand.
My goal is to bleach and use sodium sulfide toner (like dipositif on Flickr). The question is, does it matter what bleach process I use??
I have Adorama paper but plan to get some Slavich Bromportrait 80 since it seems that the Brom papers give the most substantial toning result.
Try it out! I'd say it doesn't matter, but I've only experimented with dichromate bleach so far - and a bit with copper sulfate, but that wasn't aggressive enough to my taste, although in hindsight, it may work well for mordancage (but that's an entirely different can of worms).
As for sepia toning: I always use a thiourea sepia toning (if I want sepia that is), which works on every paper as far as I can tell. The extent of toning depends on how far you bleach back the image and the hue (varying from greenish yellow to warm brown) can be varied with the ratio of NaOH:thiourea.
That's great!
I'm very curious about this process, specialy bacause it uses very few chemicals and as you've mentioned, easily to find.
Is there anything I have to look while developing? I mean... because it's made by inspection, do I have to pay attention to any particular stage of the process?
Also, at n.5 "clearing solution for about a minute" is this one minute done under the red safe light?
From n. 7, everything is made in normal light condition, correct?
Many thanks!
Mauricio Sapata
www.mauriciosapata.com
Wow, very cool!
Thanks for posting a complete process with specifics!
Tin Can
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