Re: test images: screw-in BLB UV box

From: [email protected]
Date: 07/10/05-04:24:56 PM Z
Message-id: <>

Yes, I am using Pictorico OHP; and the new cyanotype (Mike Ware's), another detail I forgot to mention this time. I do agree that the digineg density is where I need to focus attention next...along with coating practice.

Thanks very much for the practical input! JT

Judy Rowe Taylor
Mukilteo, WA
Art is a voice of the heart, a song of the soul. or
> >>> 07/10/05 1:31 PM >>>
> >>...
> I really am enamored with the very dark navy blue tone I was able to get
> in the area that was not covered by negative (i.e., only glass between
> UV source and sensitized paper) so am wondering if the Pictorico is the
> problem - maybe the 13 watt bulbs just aren't strong enough to penetrate
> the substrate or it is my diginet...>>
> Judy,
> I took a quick look at the test strips, a couple cyanotype examples and
> one of the POPs.  I'd suggest to you the UV source is not intense enough
> or the exposure times not long enough (although already excessive IMO). 
> None of the prints appear to reach d max except in the surround even
> given your long exposures.  I've used Pictorico OHP successfully for
> diginegs for both cyanotypes and van dyke brownprints (gum too) and
> while it does block some exposure I get more reasonable exposure times
> with negatives I suspect are denser than yours.  (I'm using a NuArc
> 26-1K, the sun, or 1000W quartz halogen lamps.)  So, I don't think the
> OHP is the main culprit.  You are using the OHP rather than backlight
> film (which does block considerable UV I'm told) when you refer to
> Pictorico?
> Were the cyanotypes solarizing and the POPs bronzing in the shadows as a
> result of exposure before you processed them?  Those tend to be good
> indicators of sufficient exposure with negatives suited for the those
> processes.  If the cyanotype shadows solarize, the maximum density of
> the shadows will then generally match the surround after processing. 
> Ditto the bronzed POP shadows and surround.
> I also doubt your negatives have the proper densities for these two
> processes.  Among other reasons I'm basing that statement on the POP
> image with the wedding hat.  The midtones and highlights look pretty
> good there but I don't see the nice deep tone anywhere in the shadows. 
> (POP really needs a dense contrasty negative.)  The very dark cyanotype
> and the huge jump in apparent tone between 0% net density and the
> adjacent step on your digineg step prints indicate this to me as well. 
> You probably need to adjust your cyanotype curve but that can't be done
> properly until the exposure is sufficient for the process.  I'd
> investigate a different UV exposure source unless your OK with extending
> the exposures even further (although now an additional hour will only
> gain you 2 steps, and + 3 hours will gain you only 4 steps, etc.).
> Joe
Received on Sun Jul 10 16:25:05 2005

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