[alt-photo] Re: Dmax for silver paper

[Richard Knoppow]

----- Original Message ----- 
From: "etienne garbaux" <photographeur at nerdshack.com>
To: "The alternative photographic processes mailing list" 
<alt-photo-process-list at lists.altphotolist.org>
Sent: Friday, January 13, 2012 2:22 PM
Subject: [alt-photo] Re: Dmax for silver paper


> Pierre wrote:
>
>>Does any body knows which silver paper gives the highest 
>>dmax? (fibre or RC)The latest ilford multigrade art 300 
>>paper gives me a 1.5 Dmax (measure by my X-rite 810).From 
>>what i understand, the higher the dmax, the more shades of 
>>gray you get.I read that the highest Dmax a silver paper 
>>can give is 2.2. Is that true?
>
> Is your X-rite properly calibrated?  That needs to be done 
> pretty much every day (or every time you use it).  You can 
> get a set of calibration standards from X-rite.
>
> Yes, glossy silver-gelatin materials finished full-gloss 
> by being squeegeed to glass or a polished ferrotype plate 
> to dry traditionally have been able to produce Dmax in the 
> 2.1-2.2 range.  Matte or textured paper, or "glossy" paper 
> that is not ferrotyped, are only capable of 1.5-1.8, 
> depending on the specific surface finish.  You can wipe a 
> little light mineral oil (from the drugstore) onto the 
> surface of a matte or textured print before measuring it 
> to give you an idea what the Dmax would be if the paper 
> had a glossy ferrotyped finish.
>
> Art 300 has a textured matte "eggshell" finish  -- so a 
> Dmax of 1.5-1.6 is the best you can do.  Note also that it 
> is a non-baryta paper, so the base reflectivity 
> (brightness) is lower than with baryta papers.  If you are 
> after the maximum density range in a print ("more shades 
> of grey"), you want to use the brightest paper you can 
> find as well as a high Dmax.  As far as maximizing the 
> print density range is concerned (and thus the "shades of 
> grey"), extending the range at the top is just as 
> important as extending it at the bottom.
>
> Are you toning your prints with Selinium toner?  This will 
> often give an increase in Dmax.  But again, 1.5-1.6 is all 
> you can expect from any paper with an eggshell finish.
>
> Note that it takes well-designed lighting at the display 
> location to take advantage of the full 2+ Dmax.  Further, 
> it is entirely possible to make breathtaking prints with a 
> Dmax of only 1.4-1.5.  This is about all you can get out 
> of Pt prints, for example, and many folks find them 
> entrancing.
>
> So, yes, do learn sensitometry/densitometry and how to get 
> the full range out of your materials -- but don't get hung 
> up thinking you can't make good prints unless they have a 
> Dmax over 2.0.
>
> Best regards,
>
> etienne
>
     Its interesting to look at the _transmission_ density 
of papers. Sometimes  you will find that there is gradation 
in the shadows that is not visible by reflected light. This 
is especially true of matt surfaces. As has been pointed out 
the surface texture affects Dmax and only a ferrotyped 
glossy surface will display the darkest gradations and even 
that will sometimes not display what you can see by 
transmitted light. Its possible to get a wider range of 
brightness out of prints than it usually seen by 
illuminating in a light box so that the illumination is 
stronger than the ambient light. Such prints must be made 
for this kind of display and will appear to be too dark and 
too contrasty by ordinary illumination. The surface should 
be as close to specular as possible meaning ferrotyped 
glossy.
     The nature of the substrate is important; normal papers 
have a highly reflective substrate, the material depending 
on whether they are "fiber" or or RC, both substrates serve 
the same purpose. Some papers have been made without the 
substrate, for instance to allow folding without cracking. 
The highlight brightness of these papers and general 
contrast is lower than conventional papers, they look a 
little like carbon prints since there is some surface sheen 
from the gelatin.
     In his now rather old book Dr. Richard Henry tested 
several kinds of papers and found that the silver content 
had no relationship to Dmax, the darkest papers having 
relatively low silver content. He also found little 
difference among developers. If the developer is not overly 
diluted it should produce sufficiently dark blacks. Also 
note that if you much overexpose paper the Dmax will usually 
be darker than can be obtained in a normal exposure.
     FWIW glossy papers seem to test around 1.5 to 2.0, a 
few a little darker and matt surface significantly lighter. 
Kodak used to show contrast ranges of papers with similar 
emulsion but different surfaces. It showed that the 
difference between glossy and full matt was as much as a 
paper grade.

--
Richard Knoppow
Los Angeles, CA, USA
dickburk at ix.netcom.com