Effect of Dry-down in Highlights, Midtones & Shadows on Fibre Paper
I agree with Kevs that dry-down will reduce the contrast of the print. If you use Ilford MGIV FB, or many other current papers, most, but not all of the print will dry darker, and the percentage difference will vary depending on the tone in question. I found that the highlights and midtones will be darker, in terms of reflection density, by about 0.02–0.04 logD. For a very delicate highlight, say of 0.05 logD, as a percentage, this would represent 40-100% difference. The 0.02 difference on a midtone, of perhaps density 0.60, represents only about a 3% difference.
Originally Posted by kevs
You will find, however, that deep shadows will actually dry lighter, and not darker—by about 0.02 logD, too.
Here is a couple of examples I just did this afternoon, on a previously processed, and fully dried sheet of Ilford MGIV FB WT. I inserted it, part way, into a bath of water for 15 minutes, then I took it out, squeegeed, and snapped with a digital camera, so that you could see the difference between the wet and the dried part. First, let's look at highlights and midtones, focus on the dividing line between the dry and the wet area:
As you can see, the difference on steps 24–17 is small, but very clearly visible, and would be far more striking in a real picture, than on a step-wedge. This is the key aspect of dry-down that most of us will try solving. Notice, that around step 16 the difference becomes less visible. Now, if we look at the effect on deep shadows, the opposite happens! Deep shadows dry lighter than when wet. Starting at about step 13, the difference should be visible, however not many people care about deepest shadows or dMax, so this aspect of dry-down is usually ignored, but it contributes to the overall loss of contrast. By the way, I had to increase the overall exposure on this photo to make it clearer, limitations of my digital camera, hope you can see through the glare:
As long as you aware of it, you will be able to handle it with ease. The best way is to dry a print, then assess, as others have wisely recommended.
Next to that, you could reduce the base exposure by 4-8%, after you established what yields a good looking print, while it is slightly moist—it is always better to squeegee it first, and to let it rest for a few seconds, to avoid the major glare. Make sure you are using a realistic amount of light when previewing your prints, not too much, and not CFL, preferably not halogen, or anything with too much UV. This exposure reduction solves the problem of muddy highlights, however, this technique does not compensate for the slight loss of contrast. In fact, blindly reducing exposure by 4, 8, or 10% will often lighten the deep dark accent shadows even further, and so it contributes to another loss of contrast, and that sparkle is about to vanish... Selenium toning will help overcome some of that, as it will darken midtones a bit, and shadows a lot, as much as 0.20 logD with this paper. Alternatively, you could just increase the final contrast, using your filter settings—but watch out, as increasing contrast using speed-matched filters (or heads) will also make the highlights a little lighter, so it may not be necessary to reduce the base exposure as much, or not at all, in that case.
Sorry about the awful quality of the photos in my post.