Ascorbic Acid / Effects On Fog & Stain Of Pyrocat-HD Negatives

[Flauvius]

Does the addition of ascorbic acid to Pyrocat-HD reduce inherent base fog or does the addition of ascorbic acid - 5mm of 5% to 100mm of Pyrocat-HD simply reduce Pyrocat-HD's stain?

Flauvius

 

[sanking]

Let me comment further on this.

The addition of ascorbic acid is seen first as a loss of maximum density in the highest densities, not in the lowest densities, and even then only when measured by UV. For Blue sensitive processes the loss of stain is compensated by the greater energy provided by the synergism of ascorbic acid in the mix. The result is that for Blue sensitive processes there is never a reduction in maximum effective printing density with added ascorbic, even with loss of the stain.

However, to get more precisely on point, let me say this again. If you like the stain, which I value highly (especially for UV sensitive processes), do not add more than about 10-20 ml of a 1% solution of ascorbic acid per liter of working Pyrocat-HD solution.

Sandy

The addition of ascorbic acid will reduce stain, beggining in the lowest densities, and moving up the scale as ascorbic acid is increased, until the stain is completely eliminated. So, a little ascorbic acid will reduce general stain, but more will begin to reduce image stain.

Jay

 

[Flauvius]

Ascorbic Acid For Pt/Pl Printing?

Sandy:

What is the purpose in adding ascorbic acid to Pyrocat-HD when the negatives - Efke PL-100 - are to be used for pt/pl printing?

Flauvius

 

[sanking]

With normal development, including minimal agitation, you don't need the ascorbic acid, and I don't advise it.

For Extreme Minimal Agitation and Semi-Stand the ascorbic acid may reduce slighlty B+F Stain with high speed films. Since B+F stain is just extra printing density, you might want to avoid it Especially with UV processes, since extra printing density with UV processes is on the order of minutes, not seconds as with silver processes. So the extra effort may be worth the trouble. But one way or the other, no big deal. Mainly, the biggest thing is to just expose your negatives well, and develop for the right time.

Sandy

Sandy:

What is the purpose in adding ascorbic acid to Pyrocat-HD when the negatives - Efke PL-100 - are to be used for pt/pl printing?

Flauvius