flashing paper for printing b+w

[Serge J-F. Levy]

I am looking for some guidelines on how to flash the paper base before printing for best effect. I am working in a community darkroom where I will be lucky to have a an extra enlarger with a lens in it. I want to flash the paper to give a little extra detail in the highlights with information and possibly an ever so slight tonality to the brightest of highlights on the paper WITHOUT affecting the base (in other words keeping the base as white as possible). Can someone offer me some guidelines to create a test or how best to do this?

Thanks,
Serge

[robc]

flashing was and is used to good effect with graded papers. With VC paper it is not usually necessary since you if you want to locally reduce contrast then you can expose part of the print with the contrast settings turned to a softer grade. This has a very similar effect to flashing on graded papers which only affect the mid to higher tones.

So if you are using VC paper then use a softer grade on your highlights.

If you are using graded papers then you need to make a test strip to see where your threshold point is. Usually this means you put the head to top of column and have some diffusing material under lens. Then make a test strip at a small aperture of 1 second intervals. Develop the strip and your flash time will be the exposure one before the one which shows the faintest of tone on the paper base. You will need to let the paper dry to determine this as dry down will kick in. Every time you want to preflash you will need to set the enlarger at same settings as for flash test strip. If you have some neutral density filters you may not have to move the head up but you do not preflash with your negative in the carrier as this will mean you will need to make a test strip for preflash time for each negative and besides you would not get an even preflash if neg is in carrier. i.e. by not having a negative in the carrier you only need to test once providing all other variables remain constant.
You can adjust the flash times to taste but if you go over the threshold exposure time then you get fog on paper base. You may get fog anyway and have to reduce the flash time.

remember that preflash will affect highlights and local contrast throughout the print and not just the sky or main highlights unless you dodge the rest of the print when you make the preflash.

VC paper is much simpler to achieve the same thing by burning in the highlight areas only using a soft grade.

[Eric Woodbury]

I put a piece of white plexiglass in front of the lens, in a filter holder if you have it. This works so well. You don't need another source and you don't need to move the negative or the paper. You will find this to be a very delicate control. Sometimes my flash is so short that it is almost invisible alone. But it can work miracles. Also, it can be important with some negs to only put it in some places and dodge out the rest as it can kill a sparkling highlight.

[Louie Powell]

Serge -

Flashing is a very helpful tool, and contrary to the view expressed by Rob, I find it to be useful with VC paper. Flashing can produce a contrast change of about 1/4 grade - and in my opinion, it's easier than changing filters.

Flashing can be done either prior to or after the main exposure. I usually flash after the main exposure and after any additional burning called for by the image.

You don't need a separate enlarger. I have a sheet of heavy cardboard with a large hole cut in the middle. I glued a sheet of drafting vellum to the cardboard. When the time come to flash, I simply hold the sheet under the lens, turn on the enlarger (a foot switch is helpful but not essential), and give the print a short additional exposure - typically 10%. The negative remains in the enlarger - but because the vellum acts as a diffuser, the only thing that gets through to the print is raw light.

Note that the process is inherently experimental, but the main variable is the opacity of the diffuser, so after experimenting a bit, you can quickly arrive at the amount of exposure required by your setup.

[Ben Calwell]

I've used a white styrofoam cup over the enlarger lens with good success. It gives nice, soft, non-imaging forming light.

[ronald moravec]

Just wire up a 15 watt bulb to a ceiling fixture above your enlarger bench. Control it with an electronic timer that goes to 1/10 sec.

Now take a sample paper under the bulb and flash in 1/10 sec steps . Develope and see when the paper base starts to turn grey. Back off one or two steps and you have the most flash you can give this particular paper .

If you can`t go to 1/2 sec, put some tracing paper under the bulb and repeat test.

No rocket science required.

[paulr]

"Agfa #6 graded paper (possibly the hardest paper ever made)"

there's a legend that minor white challenged a group of his students to print a particularly soft negative. even after using all the tricks in the book, none of them was able to get a decent print. then minor exposed a sheet, walked over, peed in the developer (to his students' horror) and pulled out a perfect print (to their amazement).

what he didn't tell them is that he'd taken the paper from his secret stash of grade 6.