Pre- and postflashing

[luxikon]

Have pre- and post-flashing identical effects on exposures?

 

[jovo]

IIRR, according to Howard Bond or Bruce Barnbaum (I don't remember which), it makes no difference whether you flash before or after printing the negative. However, since the purpose is to bring the paper up to the threshold, but not over it, of the first tone above paper white, it seems more intuitive to flash before printing.

 

[Steve Smith]

it seems more intuitive to flash before printing.

It does to me too although logically it makes no difference.

I think if I was exposing then flashing, half the time I would make the exposure then forget about the flashing part and put the paper straight into the developer.


Steve.

 

[doughowk]

A possible workflow would be to determine your paper's threshold exposure level. Then pre-flash several sheets of paper placing those in another box or paper safe. You can then use those for a printing session with high contrast negatives. This should at least get you to a good working print; and you can make other adjustments to achieve the final print.

 

[luxikon]

That's a good idea, thanks.

Klaus

 

[jovo]

... Then pre-flash several sheets of paper placing those in another box or paper safe. You can then use those for a printing session with high contrast negatives....

I may not be correct about this, but I also seem to recall that the flashed paper does not retain the latent pre-exposure indefinitely. To be safe, then, it's probably best to flash just for the immediate session of printing.

 

[Ronald Moravec]

Preflash with a 7 watt bulb in the ceiling over your bench. Use a enlarger timer that oes to .1 sec.

Or use a different enlarger as light source.

The way to find the threshold is to shield part of the paper and make short exposures cumulative on the other. Process and find the step where it starts to go grey compared to the unexposed side, Then back off or you will not get a true white in the print.

IIRC the the time I use is .4 sec, F 16, 75 watt enlarger bulb, enlarger set to 11x for 35 mm.