Re: URL for platinum gum comparison

Chris,
Help us here with the apparent discrepancy of the 3% cabon gum prints one
with "just curved negative" and the correctly curved version. Was the
exposure and development times constant? The graininess seems like a result
of loner exposure and longer development time. From the look of the prints
it seems that you gum layer thickness is not consistent. Did you measure the
volume of the coating solution and cover the same area of paper?
In my experience the thinner the gum layer the better is the smoothness of
the transiton between values.

I also have done a few additional back exposure experiments, trying to
arrive at best possible print on plasctic. This time I took a magnifying
glass to the print. It became obvious that my carbon/gum mix is poorly
dispersed, with clumps of pigments suspended in the matrix. I think I am
going to try a premixed watercolor for this.
This aside I could clearly see the continuous tones of gum/pigment layers.
I also made some step tablet exposures on paper, although this time with
thalo blue mix that I use for tricolor, I just had some paper coated and
handy. I get a nice gradation of tones from the pure paper to the full dark
(not so dark in absolute sense). Close examination of the print under a
magnifying glass shows a pattern of dots of pigment in all tones, it just
appears that there is more dots in dark areas and less in lighter.
Marek

>From: Katharine Thayer <kthayer@pacifier.com>
>Reply-To: alt-photo-process-l@usask.ca
>To: alt-photo-process-l@usask.ca
>Subject: Re: URL for platinum gum comparison
>Date: Mon, 01 May 2006 10:13:49 -0700
>
>Agreed. I'm sure of this (that a print rivaling the tonal scale of
>platinum can be achieved with two gum coats) from my own experience, but
>have never done a direct side by side comparison with platinum, so will
>look forward to seeing yours.
>
>What I don't understand (and this goes with the usual caveat that looking
>at jpeg rather than actual print makes any interpretation tentative) is
>that the print that's made with the "correct curve" seems grainier than
>the print made with the same coating mix but a different negative. I can't
>think of any logic of the gum process that would explain why that should
>be so.
>Katharine
>
>
>On May 1, 2006, at 8:21 AM, Dave Soemarko wrote:
>
>>And it is not just the matter of tonality either. If it were, we can
>>adjust
>>the tonality/curve either digitally or by positive/negative masking in
>>the
>>traditional way.
>>
>>But the fact is that when you do a gum print (at least a traditional gum
>>print with analog negative), somewhere after the midtone and near the
>>highlight, you get grainy effect. Depending on the paper and sizing, the
>>grainy effect might not be too pronounced (so I don't mean very rough,
>>coarse effect, but the effect can be seen). This is because of the gum
>>layer
>>is near the top of the tooth (or top of the "punk hair" using the model
>>that
>>I used before. The tooth or punk hair does not have equal length like a
>>true
>>nicely trimmed punk hair, but I will get to this later in the summer).
>>
>>You can see this grainy effect even in a simple print using a step
>>tablet.
>>When one see that, one can tell already that a single coat gum cannot
>>show
>>the same look as Platinum because the difference is not only on tonality
>>but
>>on graininess as well (and I am not saying which one is better because
>>that
>>depends on the object/purpose of the printing and personal preference. I
>>am
>>talking talking about the technical side of it).
>>
>>However, if one understands the concept of duotone and have control of it
>>in
>>gum process, I believe one can achieve the same tonality and the same (or
>>perhaps almost the same) smoothness with gum compared with Platinum.
>>
>>When I setup my printing environment again, I will ask if Pt/Pd printer
>>might be interested in a test. What I will need is an original negative
>>from
>>you (one that have full tone but is not so important for you (just in
>>case
>>there is a loss) and preferably one that you have a duplicate) and a
>>Pt/Pd
>>print from you. If you are interested, please let me know (either now or
>>then).
>>
>>
>>Dave S
>>
>>
>>-----Original Message-----
>>From: Christina Z. Anderson [mailto:zphoto@montana.net]
>>Sent: Monday, May 01, 2006 11:05 AM
>>To: alt-photo-process-l@usask.ca
>>Subject: Re: URL for platinum gum comparison
>>
>>Positively--I decided that until I had a carbon print for comparison, I
>>would choose the process that would make gum look the worst and compare,
>>to
>>weight the comparison away from gum. The other reason for using pt/ pd is
>>that it gives such an incredibly long tonal scale, especially in the
>>highlights where it shines and glows with delicacy, it would be a good
>>indication of long tonal range to compare with a short tonal range
>>process.
>>
>>I can get with both salt and pt/pd close to 31 steps on a 31 step tablet,
>>where gum is somewhere between 9 and 12.
>>chris
>>----- Original Message -----
>>From: "Yves Gauvreau" <gauvreau-yves@sympatico.ca>
>>To: <alt-photo-process-l@usask.ca>
>>Sent: Monday, May 01, 2006 8:58 AM
>>Subject: Re: URL for platinum gum comparison
>>
>>
>>
>>>Christina,
>>>
>>>the platinum print doesn't seem to have the same texture (none) as the
>>>other prints which makes it a bit difficult to compare don't you
>>>think?
>>>
>>>Regards
>>>Yves
>>>
>>>
>>>----- Original Message -----
>>>From: "Christina Z. Anderson" <zphoto@montana.net>
>>>To: "Alt, List" <alt-photo-process-L@usask.ca>
>>>Sent: Monday, May 01, 2006 8:45 AM
>>>Subject: URL for platinum gum comparison
>>>
>>>
>>>
>>>>http://www.loris.medici.name/Christina_Anderson/ Gum_Platinum_Compare.
>>>>jpg
>>>>
>>>>Here 'tis.
>>>>Chris
>>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>>
>
Received on 05/01/06-12:22:08 PM Z