[Alt-photo] Re: DAS

[Marek Matusz]

Kees, Thanks for the extra work, however I can not get to the website. I did more reading on the two APUG threads and I am coming to a conclusion that what I am seeing is a known and reported property of the carbon printing, known as loss of highlight. I think it is more pronounced with DAS, then with dichromate. Looking at my test strips I would conclude that my dichromate strip is slightly fogged, as the dichromate would perhaps be always somewhat fogged and that's why there is more gradual steps. Also the deeper you print (more penetration of the emulsion) the less pronounced the effect, so I am trying less DAS in the sensitizer. I made some glop with less pigment and it showed more gradual progression as expected, but it is really because of the first step has lower pigment and so the lower density. However this kind of print would require DMAX  of the negative to be above 3, not practical with my setup. That brings me to the other observations that I made by reading the APUG threads. The original ultrastable printing was done with a imagesetter negatives, actually with DMAX at 3 and digital in nature. The final image was also made of 4 LOW density prints (CMYK). I can see how nice low density prints could easily be made with DAS sensitizer. The loss of highlight detail would also be much less visible as 4 different prints would be superimposed resulting in a much smoother progression of tones. I have tried eliminating all the additives and changing pigment sources and all the time I see this loss of highlight detail, kind of pronounced once you get to the full print density. I am really waiting to see your test strips, to see if you could get full print density in one pass.  Marek
 > From: workshops at polychrome.nl
> Date: Tue, 30 Apr 2013 10:49:42 +0200
> To: alt-photo-process-list at lists.altphotolist.org
> Subject: [Alt-photo] Re: DAS
> 
> Hi Marek,
> 
> I did a quick step tablet test with the group buy DAS. I don't see any of this highlight clipping you are observing.
> 
> http://polychrome.nl/techlog/apug-group-buy-das
> 
> Kees
> 
> 
> 
> On 27 apr. 2013, at 03:39, Marek Matusz <marekmatusz at hotmail.com> wrote:
> 
> > Kees DAs was added to the glop at 6% basis dry gelatin I am including scans of my test prints and a perfectly normal dichromate sensitized tissue with typical nice gradation of tones. I have done a 3 minute and 6 minute exposure of DAS sensitized tissue and you can see the expected density shift, but the effect is still there. I am almost thinking it is some kind of side reaction with some chemical that is in my glop mixture. I am making just sugar/gelatin/pigment DAS tissue. ANy ideas of how to go next (less pigment/DAS?). To that effect I flashed the tissue and it seems to have done the trick. My flash was a bit too long (at 1sec), because it fogged the print too much, but it definitely gave me more gradual tone gradation, actually the contrast is way too low as it would requitr negative of logD of over 3https://plus.google.com/photos/105732508998271877151/albums/5871332081567167153?authkey=CLvJ1J76nZjjhQE Marek
> 
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