How long to leave incorrectly flashed paper

I'm an idiot.

Last night while dealing with other frustrating issues in the darkroom I preflashed 10 sheets of Ilford WarmTone FB 8x10 at grade 1, or did I? Ahhh!

I left the filter out giving the paper about twice the exposure of a preflash. Given the relatively low level of the exposure, even with the filter out, do you think it would be safe to wait a week, let the latent image dissapear, and then do the preflash again and use the paper?

Why do you think a latent image would disappear in a week?

I can't remember where but I'd read an article on flashing and fogging before that suggested that flashing paper had to be done for each session; that paper emulsions don't hold the latent image for very long and that it would probably dissappear in a few days.

I know film is a different story but it would make sense that paper emulsions wouldn't generally need to hold that image for more than an hour or two at most.

Mattg said:

I can't remember where but I'd read an article on flashing and fogging before that suggested that flashing paper had to be done for each session; that paper emulsions didn't hold the latent image for very long and that it would probably dissappear in a few days.

I know film is a different story but it would make sense that paper emulsions wouldn't generally need to hold that image for more than an hour or two at most.

Click to expand...

g'day Matt

i've never heard of or read such a thing and i doubt it, but you could always do a test

somewhat like a fogging test with a coin, expose several sheets, process one immediately, one in a week and one in a month

Thanks Ray,
Yes I could do a test so I'd know in future. Unfortunately I've "tested" quite a bit of expensive paper at this stage, and not systematically. I was hoping that, given the relatively small exposure the paper had received, the fog would dissappear fairly quickly.

BTW I'm often up at Lemon Tree Passage for holidays with family. Maybe we could meet one day at Seaham or somewhere else photogenic.

Mattg. I too have never seen anything in any thread or book on photography which led me to believe that the flashing efffect ever disappears. There are some very knowledgeable subscribers/members here and some of them may give their views and the photographic theory which underpins it.

As I understand it once a quantity of light has been received by the emulsion, no matter how small it cannot "fade away". It's an irreversible process.

Whether the flashed print can be "rescued" and made useable for printing is of course another matter. Maybe somebody(ies) will suggest what you might try.

pentaxuser

pentaxuser said:

Mattg. I too have never seen anything in any thread or book on photography which led me to believe that the flashing efffect ever disappears. There are some very knowledgeable subscribers/members here and some of them may give their views and the photographic theory which underpins it.

Click to expand...

I would be interested to know if this is the case. With my current setup I flash paper with the same enlarger that makes the prints, but with the head wound all the way up. It's always annoying to run out of flashed paper then have to reposition and re-focus the negative, but I don't like flashing large batches in case there is some left over at the end of a printing session.

Ian

hi guys

i would question why is all this flashing being done regularly?

if you need so much pre-flashed paper maybe you actually have other problems that should be addressed

some of the flashed paper may be saved by over printing and bleaching back the highlights

Mattg, Port Stephens is a beautiful part of the world, we consider it to be part of our local area, it's quite a buzz to see mention of a local town on an international forum

thnx
Ray

Hi Ray,
almost all my printing at the moment is of urban scenes at night. I tend to give a lot of exposure to the film and normal development. I started using it with Galerie as a form of contrat control. For night scenes it lets me control the highlights immediately around sources of light like lamps while also reducing the main exposure and opening up the shadows.

I haven't found a great need for it in daylight photography but do occasionally use it.

Ray Heath said:

hi guys

i would question why is all this flashing being done regularly?

Click to expand...

Ray - leaving school jokes about flashing aside ... I use quite a bit of flashing, but only as a part of the creative process, not because I have to (ie in a high key interpretation of a negative to reduce contrast). So the use of flashing doesnt have to mean there is something wrong.

With regards to the paper image disappearing - I may be WAY off course here, but surely light is light? if paper is exposed to light, it is exposed to light. I dont think it's going mend itself no matter how long you leave it.

You could always save the paper for use with high SBR negatives.

I think you can use Benzotriazole to cut back from fog - maybe this will work here, too? (However, you would end up with a higher contrast and slightly blueish tone IIRC.)

Simon

Found it!!

I knew I've read something about pre-flashing wearing off somewhere, so I've looked through my photo literature, and finally found it.

Andrew Sanderson's "Night Photography" states on page 89 after a description of the techniques for pre-flashing over several pages: "One point I should mention is, don't pre-flash a lot of paper in advance, the effect of the flashing will wear off fairly quickly (days), only flash what you can use in one session of printing."

I've never tried this personally, so I can't verify his statement. I am just happy about finding the source of my faint recollection of having read this, and thought I should mention it.

g'day Matt

i'm surprised at the small number of posts to this thread

if you'd had the words 'pyrocat', 'stand development' or 'what's the best ...' somewhere in your initial post youd have gotten lots of opinions/dissertations/but listen to me i know the secret/magic bullet and you don't responses

Leon, i just thought that too much might be indicative of other problems, i accept your rationale

Personally I think it will largely fade... I think that a normal "flash" exposure will not last that long, though you exposed for a bit longer than that.

You have an opportunity to inform us. Develop and fix a sheet today, tomorrow, two days from now, next week, and next month and let us know!

MMfoto said:

Personally I think it will largely fade... I think that a normal "flash" exposure will not last that long, though you exposed for a bit longer than that.

Click to expand...

MMfoto - I'm not trying to be picky or contrary with you here, but what would lead you to think this (or anyone for that matter?) There have been recent articles about exposed films dating from the 1950s or longer that have recently been developed with good strong images on them. I cant see that paper would be overly different, it's still silver held in a gelatin emulsion. I'm aware that paper flashing doesnt provide enough light to form an image, but it does enough to change the contrast range of the paper,therefore, as far as my (maybe skewed) understanding goes, the light is sufficient enough to make the same chemical changes, just not as much - so why would this fade away?

It would be great if someone could explain this either for or against using scientific points ..... any takers? I might PM Photoengineer to see if he might be able to enlighten us.

Leon said:

? I might PM Photoengineer to see if he might be able to enlighten us.

Click to expand...

Well - I have done, and it appears that the situation isnt as obvious as a clear "yes it does" or "no it doesnt"

It would seem that the chemicals that enable film to maintain a stable latent image are quite expensive, so manufacturers tend to use this much more sparingly when making paper as it is assumed that in most circumstances, paper will be developed immediately after exposure.

That said - Ron went on to suggest that, "Newer papers have better latent image keeping than old ones, but I could imagine that an Ilford paper made by a first-rate company would be stable but an inexpensive paper made by a third tier company might have an image which fades."

so there is the answer. A latent image does fade and it yet doesnt.

It all depends. Just like life

I can tell you that I developed half a sheet of the incorrectly flashed paper three nights after I made my mistake and saw no fog at all. This doesn't really prove much as it's just possible that even with the incorrect flashing there wasn't enough exposure to fog the sheet.

Next time I'm in the darkroom I'll expose a sheet for a midtone, then develop strips of it over time using standardised development to see how long it takes to get below the level of visible fog.

Mattg said:

I can tell you that I developed half a sheet of the incorrectly flashed paper three nights after I made my mistake and saw no fog at all. This doesn't really prove much as it's just possible that even with the incorrect flashing there wasn't enough exposure to fog the sheet.

Next time I'm in the darkroom I'll expose a sheet for a midtone, then develop strips of it over time using standardised development to see how long it takes to get below the level of visible fog.

Click to expand...

Do you have any of the paper un-flashed? If so, why not work out an exposure for a given neg (preferably one with lots of important highlight tones) on the un-flashed, then use a sheet of the flashed for the same exposure to see if highlights are affected?

Leon said:

Do you have any of the paper un-flashed? If so, why not work out an exposure for a given neg (preferably one with lots of important highlight tones) on the un-flashed, then use a sheet of the flashed for the same exposure to see if highlights are affected?

Click to expand...

The short answer is, no. It porbably wouldn't be a bad way to test in my current predicament, but because I can't do it I'll do the midtone test that should show more accurately/graphically just how the latent image might fade over time.

I will add my limited opinion to this:

I think that the idea of flashing a paper is that the emulsion has a threshold level of exposure below which, no change from base white will register.

The ideal flash level is one which is just below the level which will show any difference from no exposure at all.

In order for the highlight detail to register, it is combined with the flash level to give a total level just above the threshold.

If you have a flash exposure only, normally it would be below the threshold and in itself can fade. Why, I don't know but I would think that the reason that films exposed decades ago can still produce good images is that this exposure is well above the threshold level.

I have no actual experience of this, it's just my cobbling together of all the ideas I have read on paper pre-flashing.

Steve.

Mattg said:

The short answer is, no. It porbably wouldn't be a bad way to test in my current predicament, but because I can't do it I'll do the midtone test that should show more accurately/graphically just how the latent image might fade over time.

Click to expand...

wowa Matt, now your confusing the issue

you started by asking if flashed paper would hold the exposure, now you don't know if the paper was even pre-flashed and now your talking about exposing for a mid tone, that's a different thing altogether

stop, rethink, how did you determine the original exposure to pre-flash the paper?

did you do a test strip?

did you find a time that gave just a bare hint of exposure?

did you guess the whole thing?

what lead you to believe you needed to pre-flash?

how did you know pre-flashing made any difference when you printed on the pre-flashed paper?

please explain your normal working method re: test strips, evaluation, determination of contrast grade (for VC papers)

Ray

Sorry Ray, I'm not very clear sometimes.

I know the paper was preflashed. I know it received too much exposure, I don't know how much.

I am able to calculate the preflash by using an RH Anlyser Pro. I run test strips for each paper and dev combo and generally do one just below what I can see wet so that when it dries I have a preflash test strip at 1/12 stop intervals. I generally use the exposure compensation setting that corresponds to the first strip with no visible fog when dry. That gives me a factor that can be apllied to any head height or focus setting.

As an example I can measure the white light with my Analyser Pro and then reduce the exposure time by 14 steps (1 and 1/6 stops) with MGWTFB to get my pre-exposure time.

My problem is I'm used to using Galerie not MG and I forgot to put the below lens filter in after measuring the white light, this is something particular to using an Analyser. What it means is that my calibration of all my exposure metering is set up to measure white light but print with filter. I didn't use the No.1 filter that a I should have and so I gave too much exposure to the paper, but I don't know how much.

When printing on the preflashed paper I am able to reduce my main exposure time by about 1 stop (compared to non-preflashed paper) while retaining more detail in the highlights, leaving just small areas of paperbase white. Of course, reducing the main exposure by 1 stop helps immensely in keeping shadows open, remember these are night time scenes. Contrast can then be judged based on what's balck and what isn't, whether those things should or shouldn't be black etc.

Without using a preflash I would have to lower contrast, either through filtration or development control, if I wanted the same level of detail around my highlights and the same black areas. The shadows would then become more murky because they are being printed at a lower grade and receiving about a stop more exposure. The difference is stark.

I know some people use split grade printing to get around this sort of problem but this hasn't been an option for me until very recently because I've preferred Galerie (the only reason I'm investigating MGWT is that Kennedy's won't import Galerie). Of course that requires dodging and buring so the effect is area specific.

In brief highlights determine exposure time, deep shadows determine contrast and I determine them in that order.

I'm not sure what you're really asking but suspect you don't like flashers?

Have a look at my APUG gallery, the night time scenes involve lots of contrast that I don't really want to mush-up by reducing film development time. Preflashing lets me get subtle detail around the light sources themselves, keeps the light sources paperbase white and opens up the shadows considerably. It's a win all round.

As I said, daytime shots don't require it to the same extent because there isn't the same degree of contrast and you're not dealing with failure of the reciprocity law (which tends to increase contrast at long times) and the shadows are lit by open sky.

The only reason I want to do a midtone test is that it may help me understand the latent image keeping qualities of the paper. It has nothing to do with preflashes.

As I said, the paper that I inadvertently gave to much pre-exposure to showed no fog after three days but for all I know it just might have shown no fog if developed immediately.