Paper Negative Reversal Process

[andy_k]

i cut more paper just yesteryday, now trying it with some highly expired Kodak Multigrade II RC. it seems much slower than the Ilfospeed 3 my previous images were made with.

also, i (actually!) measured my developer concentration, and played with the process there. my estimations on concentration were way off, a triple strength dilution (1:3 rather than 1:9 as per bottle instructions for Ilford Multigrade) is required for the image reversal to occur. strong-but-close-to-normal concentrations resulted only in an off-color fog when the secondary exposure was applied.

i'll post more results soon.

 

[erikg]

I tried this out some time ago, mostly just to see if I could make it work. I exposed the paper to a negative in the enlarger, and then reversed it, so I had a negative to negative process. It's pretty cool to do, and it would be a good pairing with a pinhole camera. I never could get fiber based paper to work without some staining. I guess that seems rather obvious but until you try it you never know for sure.

 

[SMBooth]

I never could get fiber based paper to work without some staining. I guess that seems rather obvious but until you try it you never know for sure.

Not to me, Why?

I was going to try FB paper.

 

[andy_k]

yeah i doubt the emulsion support has a huge effect on how it will respond to the process, but i've found huge differences in behavior between the Ilfospeed and Multigrade II. definitely different papers are going to respond very differently, not to mention developer combinations.

anyone have a good idea for how to make a rudimentary 6x6 step tablet? i'd really like to begin taking this process halfway seriously.

 

[holmburgers]

Andy, does your 6x6 camera have a darkslide per chance (like on a Hasselblad film back for instance)? If so, you could pull it out in increments, giving a -5 exposure on a white/gray ground each time you pull it out. If you can pull it out 11 times in the length of 6cm, dividing the film into 11 sections, the first exposed portion will eventually get +5 exposure and the intermediate sections will get +4, +3, +2, +1, 0, -1, -2, -3, -4, -5.

You could do the same thing under an enlarger, but it'd just be a bit trickier.

 

[andy_k]

man, i totally wish it did. great idea.

no the C330's are the RB67's of the TLR world, chunky, featured, and awesome. no darkslide though. however when i'm next in the darkroom i'll try that out, with a better meter on the reversing exposure that way too.

 

[erikg]

Not to me, Why?

I was going to try FB paper.

It does work on FB, but there was some staining that I couldn't solve. When you look at what the paper is going through it isn't surprising, at least to me. Don't let that stop you from trying, that was just my experience.

 

[andy_k]

The Process Analyzed

I went to the darkroom this afternoon and put some time into getting a better idea of what's going on with the reversal process, and how to try and optimize the results. For this round of tests I essentially tried to replicate the conditions that have worked in the past for me in my bathroom, and intend to further experiment in a controllable fashion rather than just guessing and checking.



This is what I came up with today. Developer was Ilford Multigrade at 1:3 dilution. Paper was some old Kodak Multigrade RC II. I set up the enlarger without filters, using a 50mm f2.8 projection lens (for speed and the size of the projected circle). The picture above shows all the stuff I exposed, first a test for max black, then the smaller strips on which I tried a nine stop exposure range. The larger strips were a dialed-in five stop exposure range in 1/3 stop increments.

For this test I began quantifying my exposure in lux-seconds to have a universal unit of comparison for the different exposure intensities between the much slower and smaller intensities which create the negative image, and the short intense exposure which induces the tone reversal.




A close-up of my results, and the development information for the big strips. As you can see, the process is sensitive to changes in pre-flash development and flash duration/intensity. My feeling is that a slightly lower developer concentration might provide better overall contrast range compared to the results I achieved today. Also, I'm curious about what, if any, effect a shorter and brighter (but same lux-second) reversing flash would have.

I can post my complete exposure data if anyone is interested, but it will likely be quite different for other paper/developer combinations. My estimations of about 0.2s flashes for the self-portraits I posted earlier in the thread seemed to produce the best results today (I calibrated the enlarger to match the measured brightness of the light at counter-top distance). Maximum black on the test strip, both negative and reversed, was achieved at ~32 ls exposure, minimum reversed density (2 stops less than max negative black) at ~ 10ls, and max reversed density (starting 1.67 stops than min rev density) at 3.2 ls and less. The reversing exposure was 64 ls for the nominal 0.2s exposure at a measured 7 EV, twice the amount of light to produce max black.

Thoughts? Comments? Criticisms?

edit: looking carefully, as I hadn't yet today--I struggled to get these tests finished with a migraine coming on, which I've only now come clear of--test strips 4 and 7 have a reasonably large difference in development and exposure times, producing very comparable and good results. As with my earlier feeling, this procedure does have a fairly wide sweet spot.

 

[andy_k]

More Testing

Alright, another go 'round, looking to see the effect of changing developer concentration in conjunction with variations in exposure.
The exposure range for these strips was from 2.5 ls to 12.5 ls (the 10 ls zone still the lightest after reversal) in 1/6th stop increments. Reversing exposure the same, other than where indicated. The first six strips were developed at 1:4 dilution, with the seventh at 1:5.


it appears to me that developer concentration has a similar effect to shifting exposure/development when push or pull processing on film; there is an inherent compromise between tonal range and tonal contrast.
it seems that at these very high developer energies/concentrations that the relatively small variations in exposure have a smaller overall effect, and need to be within a narrower range, than developer concentration.

Any input? I'd love to know what Photo Engineer might say about any of this, or anyone with more technical knowledge than i have.

 

[andy_k]

Hey again gents (and ladies?),

Quick feedback from my experience using powerful flash heads to stimulate the reversal process: it makes a huge difference. Without really having numbers to relate to the above information, or surviving visual (scannable) results to give you, I noticed a massive increase in overal tonal range and contrast using studio strobes to hit the negative image with.

The reason I don't have anything to show you to prove it is a result of my recycling of fairly old fixer in my portable paper-picture kit. Having long since dissolved even the aluminium off of the bottle seal, and smelling strongly of ammonia, the fixer somehow bleached the developed positive images from very nice looking black and white to a creme and rusty brown. No idea what was going on there, but sadly the great reversal results were lost.

Anyone else try out my approach yet? Particularly with a larger format camera?

 

[NedL]

I haven't tried it but I've been reading with interest these past weeks and hope you keep relating your experience! Neat idea to try to get this process under control.

 

[andy_k]

It appears that a functional EI of 25 produces really great latent images that are very suitable for reversal, provided that your scene is illuminated with only 2 - 4 stops of luminance range. Reversing with a very powerful strobe is unquestionably the superior method, compared to bright halogen light.

I suggest giving it a try if you're interested, see what happens.

 

[johnielvis]

I'm sorry, but I don't see how a more powerful re-exposure can INCREASE the effective ei...then again I never used multigrade kodak for my experiments--I know that it's much faster than the ancient agfa stuff that I used...

all my experience have pointed to more re-exposure and 2nd development giving more density UNLESS you are overexposing in the 2nd exposure to the point that you're gettin solarization/partial reversal or total reversal happening...that may be the case and if it's controllable, then this may be worthwhile....man so busy....but we'll see maybe I'll be able to play around and try it out myself and just see for myself what's possible...first thing I'll do though is start from scratch with the olde kodak polycontrast for the extra speed and see what various re-exposures to GROSS over re-exposure do...I'll do real object pictures though...test strips really give me no useful information on how it reacts to real objects

 

[johnielvis]

OK...tried again for the first time in a year...this time I used some kodak polycontrast I had and got a decent speed between EI 12 and 6...like 6ish...they are still drying now. So maybe this will actually be ok to do---they look very good---oh that's the ei fro human flesh to be "white"...which kind of blows out other light colored things--it's closer to ei 12 to 25 for "dark skin" the way properly exposed film looks with a blue filter

to get a "normal" looking white skin portrait, the speed is slower.

ANYWAYS, the reversals look fine--clean whites BUT the paper I have found...is fogged...all my olde paper...it is VERY old too...when I develop it with no exposure it turns grey--so this age-fogging makes it ok for reversals--I determined this AFTER I tossed the paper in the trash and turned onthe lights after testing a bunch of sheets and finding them all fogged...So--it looks like I could have used all that old paper for reversals just fine--the bleach step burns off the fog...oh well...it was like the age-fog pre-flashed it--I did not flash the paper with light.

SO...LEARN from my mistake--DONT TOSS what looks like bad fogged paper---USE IT FOR DIRECT REVERSAL!!!!

I'm going to buy NEW multigrade paper and see what I can get without pre-flashing.

 

[johnielvis]

OK here are results of experiments using FRESH, new paper (ilford multigrade RC) AND some PROPER paper developer (ilford PQ universal).

First experiment: deveoped fresh paper in safelight in the same hc-110 from last time AND also in ilford PQ universal

results: the hc-110 developed fog on the new paper == much much more slowly than the old paper, but it was developing it where the PQ universal developer had NO such fog. 2' development with these.

Second experiment: same as the first, but with paper that had NEVER been exposed to safelight and developed in complete darkness

results: same--had fog with the hc-110 and none at all for the ilford PQ.

Therefore, it's not the safelight--it's the developer. SO Lesson #1 is: use paper developer.

SECOND EXPERIMENT--EXPOSURE....shot starting at iso6 (where the last "hot developer fogged" paper looked best) and didn't get "good" results till 4 stops more exposure. All were developed using the ilford PQ as the first developer to avoid all fog.

RESULTS: slightly overexposed at iso 0.8 and a slightly underexposed at iso 1.6...so it appears that ISO=1 is the sweet spot for bright looking skin with this blue/green-sensitive emulsion. This is for NO fogging of any kind, including pre-flash.

Comparing with the last batch, there is more dmax--blacker blacks when no fog is introduced. Fog results in less dmax-this goes for fog introduced by an overpowerful first developer and should also go for pre-exposure/base fog.

Fog INCREASES SPEED and decreases perceived contrast (everybody knows that)...but the decrease in contrast really doesn't seem to be all that much--the biggest gain is in effective speed---HOWEVER--this comes at a price--the fogging decreases dmax...the black borders on the first "fogged" batch are less black compared to the latest batch.

It would seem that you can't cheat--you need a LOT of light if you want it done right, no way around it--no sense in getting less dmax (which gives the APPEARANCE of "tamer" contrast) by introducing fog--it appears to be a false economy--you may have a tamer "looking" contrast, but what is really happening is that you are decreasing your END contrast range in the paper by lowering the dmax---the paper can display less contrast and it does so.

Increasing the speed and "taming" the contrast appears to be a false economy---and it also introduces another "uncertainty" factor in the results--making it more difficult to get a decent process control down--two exposures gives two exposure uncertainties added together--this is likely enought to mess anyone up given the contrast/responsiveness of the paper. The most consistent, repeatable and reliable results will be obtained with NO pre-flash and using FRESH paper and a PAPER DEVELOPER with plently of restrainers in it for a first developer.

So in short: good results white skin portraits for this is iso=1, FRESH ilford multigrade RC, PAPER DEVELOPER--PQ universal first developer. NO PREFLASH.

to get this a hasselblad 80f2.8 wide open lit by 2x travelite 750s on full power was used. The paper was loaded in hasselblad/sheet film holders.

If you have a slower lens and bellows factor for larger format, then it appears that there is no way around it--get more strobe power of use time exposure in sunlight or powerful hotlights.

On the plus side, the paper IS DESIGNED to be exposed by a tungsten light source. so hotlights/time exposures may just be the best for this type of use...that's another experiment...using hotlights and determining ISO with them.

 

[johnielvis]

results for tungsten lights--using three par 30 halogen 75w lights (standard home track lights):

MORE apparent CONTRAST and a MUCH MUCH more "red insensitive" look to it. Somehow the "redder" tungsten lights gave a result that looked like it was lit with "less red" light--there was a red ball in both the strobe and the tungsten pics--the strobes made it look grey--kind of darker than shaded, but grey. The tungsten made it BLACK!

Also--SPEED DECREASE OF ONE MORE STOP OVER STROBES--speed needs one more stop--the similar exposure to get the same skintone was ei=0.5. These were 10 second exposures at f2.8.

Regular hot lights would give a much more favable exposure and may be better than strobes to give a more "wetplate look" to it. Time to fire up the high wattage hotlights up close and see what the best exposure time can be had....

All in all, the contrast range looks fine--there is no "contrast taming" needed--just sufficient light. The only thing that makes film superior is the faster speed.

If SOMEBODY would just come up with that source for the photobooth "super speed" paper designed for direct reversal, we would all be better off.

It's been said that Slavich makes this stuff but nobody seems to know--the photobooth people are not helpful--somehow fearful that their business will be ruined if they let out their supplier. Does anybody know where the photobooth people get their paper--The photobooth people will sell their paper but they only get it in 1.5" strips and they are not reeptive to special ordering....

 

[andy_k]

I'm sorry, but I don't see how a more powerful re-exposure can INCREASE the effective ei...
UNLESS you are overexposing in the 2nd exposure to the point that you're gettin solarization/partial reversal or total reversal happening...that may be the case and if it's controllable, then this may be worthwhile...

yeah, not sure if you saw my earlier posts but this is exactly it. the second exposure that i'm doing is not a fogging exposure in a chemical reversing process, but a solarizing exposure that i'm trying to control. the higher EI rating for the paper is just something that i'm estimating based on my test results as a more suitable latent image for my solarized direct reversal process (it's all done in one development, the paper never leaves the soup).

 

[andy_k]

i'm now quite done catching up on badly overdue darkroom projects, but as time permits me in the coming months i'll be attempting some ultra large format macro reversal images. i'll update here in the thread as progress is made.

 

[NedL]

I'm looking forward to reading them... I find this fascinating and hope to play with it myself eventually.

 

[Photo Engineer]

My search showed SCN in the FD or the SD or both. My opinion, after looking at a lot of data says it is best in the FD, but don't discount use in the SD.

PE

 

[andy_k]

hey PE, can you make any comment on what you think is going on in the solarization process, or point me toward some academic/scientific studies on the phenomenon? i'd like to do more than guess at precisely what it is that i was doing there.

for a progress update on the project to make a bigger camera for the purposes of this process, attempts to this point have been abortive. i shall endeavor to resolve this in the coming week.

 

[andy_k]

so, small update. i built a pinhole camera to take fullsize photos and did some work yesterday with 11x14" paper. results were... not ideal. the long exposure times really hinder getting adequate feedback, and i was really panicked to get the work done on a schedule. this means that my poor results with the process were probably exacerbated, but at the best of times it can be a little unpredicatable (particularly when i'm relying on my hand to do reliable timing on the second exposure).

no time to post results, not that they are good anyway, but just wanted to mention that i was still working on it.

 

[johnielvis]

OH--me too.I'm now experimenting with the ilford digital silver paper. It's sure got the high high high contrast so far and is much faster. Like ei of 12 (or more) for reversal.

 

[andy_k]

goddamn, is that panchromatic B&W paper? with an IDmax of 2.3 without toning? ffffff.... WHY ARE YOU USING GOOD PAPER FOR SCREWING AROUND??!!
also, i meter my paper at EI 25 and use a super high concentrated developer for my "controlled" solarization reversal.

 

[johnielvis]

it sure is. That panchromatic paper is very interesting stuff. With tame developer, the speed is slow, but I'm getting super high peed/solarization effects with powerful developers...to my surprise. It seems to be an "overdevelopment" type of thing going on or something. I still haven't found the high point of the high speed--but I'm running out of paper to play with. Where I want to be is using the high strength developer with normal speeds and no solarization--so I can have direct reversals with paper at a decent speed. that's what the hope is now.