RE: Dmax versus process?

Yves,

With single coat gum, one can get slightly better than 1.2 but not much more
because of the filtering effect. With very long exposure I can get to near
1.4 (I have a big file of tests and I am typing this from memory).

With double coating, one can improve dmax in a certain way but it doesn't
improve as people who have not done a lot of gum printing thinks. People
tend to think that one can print and print and print and increase the dmax
again and again, but the fact is they don't improve as much. This is due to
mechanical property that the gum layer do not stack up indefinitely.

So while gum is a chemical process if we think of the hardening of the gum,
it is also a mechanical process when we think about how the gum layer
holding on the paper. The two must work together (both in practice and in
analysis).

Dave S

-----Original Message-----
From: Yves Gauvreau [mailto:gauvreau-yves@sympatico.ca]
Sent: Monday, May 01, 2006 12:03 PM
To: alt-photo-process-l@usask.ca
Subject: Re: Dmax versus process?

Sandy,

thanks, your answer is much better then I expected. I'm surprised that you
can't get a better Dmax from gum unless this is for a single coat of course.

I always thought that density measures where dimension less??

Thanks again and my best regards
Yves

PS Thanks to Loris as well.

----- Original Message -----
From: "Sandy King" <sanking@clemson.edu>
To: <alt-photo-process-l@usask.ca>
Sent: Monday, May 01, 2006 11:32 AM
Subject: Re: Dmax versus process?

> Yves,
>
> I don't know if there is a text on this anywhere, but my own
> measurement of reflective Dmax of these type of prints suggests the
> following. This has been for prints with a full range of tones from
> the highlights to the shadows, and is for one coating and exposure.
>
> By process, the maximum Dmax that I have seen are.
> 1. Silver gelatin print on glossy paper -- log. 2.2 or higher.
> 2. Carbon prints on glossy papers -- log 2.0 3. Silver gelatin print
> on matte paper - log 1.85 4. Carbon prints on matte type surfaces -
> log 1.80 5. Albumen -- log 1.8 6. Pt./Pd. and kallitype -- log 1.55 7.
> VDB and Argyrotype -- 1.45 8. Salt Print -- 1.40 9. Gum prints -- 1.20
>
> Again, these numbers are based on readings that I have taken of actual
> prints, and will almost certainly differ to some extent from the
> experience of others. Also, toning plays an important role in Dmax of
> all types of silver prints.
>
> It might be interesting to gather more information on this with wider
> sampling, but for useful results it would have to be done in standard
> conditions and with calibrated equipment.
>
> Sandy
>
>
>
>
>
>
>
> >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 05/01/06-10:10:35 AM Z