Re: For those who are interested in making digital negatives using pigmented inksets

From: Loris Medici ^lt;[email protected]>
Date: 01/02/04-05:36:49 PM Z
Message-id: <001d01c3d189$4cb71ee0$bc02500a@lorism>

> However, 8-10 minute exposures seem incredibly long to me for digital
> negatives, considering your set-up, i.e. high output tubes used at 3"

I agree. It's long. As you make this remark I realized that my Van Dyke
chemistry is not standard:

Solution A: 27gr Ferric Ammonium Citrate + water to make 100ml

Solution B: 6gr Tartaric Acid + water to make 100 ml (the standard formula
is 4.5gr)

Solution C: 12gr Silver Nitrate + water to make 100ml

As you can see the amnt. of Tartaric Acid is 50% more than the standard (to
increase contrast). Can be this modification causing the speed loss?

> from the printing frame with close spacing. My set-up for the tests
> described in my article on UV light sources was normal output bulbs
> used at about 4" from the printing frame. Also, as you can see from
> the tests the first maximum black is at about Step 3 or Step 4,
> indicating that the tests received about 1.5 to 2.0 stops more than
> needed. And these results pretty much agree with my current work
> conditions as typical exposures for VDB and kallitype with my bank of
> BLB tubes is in the 2-3 minute range for digital negatives with a UV
> printing density of about 1.8 (from about 0.20 to 2.00).

One more interesting fact is that if I vary the exposure considerably
results don't change by the same proportions. For instance once I tried 8,
12 and 16 min. exposure with the same lith negative and only midtones and
highlights were affected - highlights more; as if the emulsion was self
masking? What can be your comments for this phenomenon?

Received on Fri Jan 2 17:40:24 2004

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