RE: Dmax versus process?

Agree. And also, in additional to subjective evaluation, we need to
understand that density alone does not tell everything, even the look or
"blackness" perceived by eye. A tranmission densitometer simply shine
(cannot think of the right word) a light source to an area and measure how
much of the light is reflected. That is all, nothing more, nothing less.

So, if you have a thick layer of colloid (in a non-technical sense) with
less concentration of pigment, the light needs to travel down the thickness
of the layer, and the reflected light needs to travel back. Let's say you
have a density of 1.8. Now if you instead have a very thin layer and heavily
concentrated pigment, the pigment might block the same amount of light, and
you might have a density of 1.8, but the look of the two are different, and
that cannot be told by density alone.

One example is if you take a jet black gouache (maybe dilute it just a
little bit for brushability) and paint it on a piece of paper, you get a
very nice black look. If you measure the density (and I did it once), the
density is only 1.5 to 1.6. But to my eye the blackness is certainly blacker
than a 2.1 or a glossy paper. But the looks are completely different.
Glossiness increases dmax in a specific way. It makes the reflection point
to one direction only, so when you use a densitometer, it cannot tell the
difference between that than a matte print which can reflect light in all
directions. It simply measures how much is given and how many percent of the
light is reflected.

Maybe I am starting to confuse again. I am poor with words. Sorry.

Dave S
 

-----Original Message-----
From: Loris Medici [mailto:mail@loris.medici.name]
Sent: Monday, May 01, 2006 11:38 AM
To: alt-photo-process-l@usask.ca
Subject: RE: Dmax versus process?

I don't do all of them but I'd bet for carbon since you can use darkest
black pigments and the gelatine layer (which can be quite glossy compared to
plain paper) is thicker in the shadows. Gloss will definitely improve dmax;
I get log 0.3 - 0.4 increase by coating semi-glossy (satin) polyurethane
over the image, glossy polyurethane may improve dmax further I presume.
(BTW, IIRC, wet thickness of my polyurethane coating is 30mils = 0.76mm...)

This is without regarding the adjective "enough" of course... It's absolute.
The answer to the question "Do you really need that much dmax?" is highly
subjective and image dependant.

Regards,
Loris.

-----Original Message-----
From: Yves Gauvreau [mailto:gauvreau-yves@sympatico.ca]
Sent: 01 Mayıs 2006 Pazartesi 18:16
To: alt-photo-process-l@usask.ca
Subject: Dmax versus process?

Hi,

say you make several prints using the same paper, maybe a step tablet to
keep it as simple as possible, what could one expect in terms print Dmax
from various process like Salt prints, Kallitype, Vandyke, Argyrotype,
Platinum, Palladium and pigment based process say gum and or carbon?

If there is some text somewhere on this, it would be fine. I know some
of you teach alt-process printing and I'm sure someone as an idea on
this, it doesn't have to be in absolute terms.

Thanks
Yves

PS. Please don't say try it out yourself...
Received on 05/01/06-09:56:56 AM Z