Hi there First of all thanx to this service. it's been quite helpful I have been printing on Illford MG iv the finish I normaly use is 'satin' sometimes after drying, the prints though matched to the right testpiece look little dark than when they are wet. Is that what is called dry down factor? thanx shreepad

-- shreepad (shreepadjoglekar@usa.net), August 18, 1999

Answers

Yes. And the section of your test strip to which you matched the print should still be in accordance with the actual print, because the test strip dies down, too. The effect seems to be a little less grave with glossy RC papers, but it is still there. You might want to use a hair dryer to dry your test strips before evaluating them.

-- Thomas Wollstein (thomas_wollstein@web.de), August 18, 1999.

I have read conflicting accounts of this phenomenon. Some say the phenomenon actually exists while others say it does not exist, that it's simply the lighting and the adjustment levels of your eyes. I now think it's a combination of both, plus that fact that a wet print seem to reflect more light anyway. I experience this annoyance as well. Sometimes I'll reprint a light print slightly darker only to find out in normal lighting that the one that was too light is just fine, and the darker one is too dark. I think the only way to tell for sure is get the blow dryer out and look at test strips at the kitchen table after your eyes have adjusted to normal lighting. Sure slows down the printing process.

-- Tony Rowlett (rowlett@alaska.net), August 18, 1999.

I've also read that this effect doesn't really exist. For something that doesn't exist, it sure has wrecked a lot of my prints! I have simply learned to print slightly lighter than looks best. Prints that look perfect in the fixer under a 40W bulb are invariably too dark when dry. I find that details come out in the highlights that I couldn't see in the "too light" print sitting in the fixer or wash.

-- Conrad Hoffman (choffman@rpa.net), August 18, 1999.

Whatever the reason, the effect is there. If you put one drop of water on a dry print, you will see that the tones change a bit. The effect is stronger with matte surfaces.

Of course, lighting will also affect the way you feel about a print. To prepare an optimum print, evaluate dry test exposures under the same lighting conditions as the actual print. In "The Print" Ansel Adams suggests a method to estimate the effect of making a print lighter or darker, which relies on viewing the print under lighting conditions that are changed for a short time.

-- Thomas Wollstein (thomas_wollstein@web.de), August 19, 1999.

yes this effect is pretty easy to see in side by side wet/dry prints, why anyone would deny its existence is beyond me. Its nothing more than a water soaked print which causes more of the white paper base to show through.

-- mark lindsey (lindseygraves@msn.com), August 20, 1999.

well the opposite is true for pearl surface in the Ilford line...I do think it's our eyes....pearl surface looks nice wet,,,then as the water sheds and drys completely a percieved lightening of the dmax areas happens....It has to do with the surface in rc papers that's why the glossy surface dry-up isn't nearly so noticeable...I've noticed also that fiber based papers (some more than others) have a dry-down characteristic that must be compensated in the print times! So here we go defining and confusing two seperate happenings! Dry-up and Dry down!

-- trib (linhof6@hotmail.com), August 20, 1999.

I have been attempting to get my mind around this since reading your question and have been trying to reason it with my high school physics...which was a long time ago. I was wondering if it has to do with the rougher coatings scattering more of light before it reaches the print surface and therefore less is reflected back to our eyes. When it is wet the water fills the depressions and sort of acts as a lens to allow more light to hit the surface and more to reflect back. More light means 'lighter' tones. If this is way off base I would appreciate knowing.

-- Andy Laycock (agl@intergate.bc.ca), August 22, 1999.

There may, in fact, be two competing effects:

1) When drying, the gelatine shrinks notably (as can be noted, among other things, in the curling of FB prints during drying). This shrinking affects the reflectivity of the silver image. It is widely accepted that this is what causes the dry-down gain in D_max.

2) Generally, the D_max of a glossy surface is higher than that of a matte surface. This owes to the fact that glossy surfaces favour specular reflections. Matte surfaces, otoh, tend to reflect light diffusely. So does the silver image. Now remember how positive densities are measured: A light source illuminates the image at 90 degrees, and a sensor measures the reflected light at 45 degrees. When the surface is glossy, and the reflection follows the rule "angle incident = angle reflected", there is practically no contribution from surface reflection to the light measured by the sensor, only the silver image reflects light to the sensor. This is the best thing that can happen, as far as the D_max is concerned. When, otoh, the surface is matte, the light is diffusely reflected in all directions, including the one to the sensor. If the silver image were the same for the glossy and matte surfaces, the D_max of the matte paper would still appear to be reduced, because the sensor detects some light from the diffuse reflection! (The same effect will, of course, also reduce the highlight density, making the highlights brighter, but this is like with pre-exposing: A lot of light reaches the sensor from the highlights, and a little more doesn't make much of a difference. When the black spots are lit up a little, this makes a relatively large difference.) Now, when there is a water film on a matte or pearl print surface, this water film is more or less a glossy surface. When the water runs off, the structured or matte surface comes out, which results in a loss of apparent D_max, competing with the gain in D_max resulting from drying down as described above.

From this, I would expect that the dry-down gain in density is most notable in papers with a thick silver emulsion and a glossy surface.

The other extreme would be matte papers with a thin emulsion. There, the surface dry-down might result in a loss in D_max not compensated for by a corresponding gain by shrinkage.

-- Thomas Wollstein (thomas_wollstein@web.de), August 23, 1999.

I think what most of these guys are saying is: if you notice the drydown in your paper, then you will know that when you use that given paper you have to compensate for it. Pat

-- pat j. krentz (krentz@cci-29palms.com), August 24, 1999.