Re: Vandyke Brown with Citric Acid

I want to mention that the working solution of this mixture, which I
will call VDB-SK, has a pH of about 4.0, by measurement with a pH
strip. If someone can measure the pH of the classic solution and post
the results I would be very appreciative.

Sandy

>I was doing some testing with a new light source and wanted to try
>Vandyke Brown with it. However, since I did not have any tartaric
>acid on hand to mix up the classic VDB formula I decided to use
>citric acid instead. After a few tests I found that the following
>formula works very nicely, with Dmax at least as good as the
>classic formula.
>
>If interested, mix as follows.
>
> Solution A
> 75 ml distilled water
> 10 grams ferric ammonium citrate
> 5 grams citric acid
> Distilled water to 100ml
>
> Solution B
> 40 ml distilled water
> 6 grams silver nitrate
> Distilled water to 60 ml
>
>When Solutions A and B are completely dissolved, just mix them
>together for a stock solution that should be as long-lived as the
>classic VDB formula. Sensitize using about 2.5 ml of this solution
>per 8X10 sheet of paper.
>
>In using Rising Stonhenge off the shelf with no acid soak I was able
>to get a Dmax of 1.45 with this mixture single coating using about
>2.5 ml of solution per 8X10 sheet of paper. That is higher than I
>have been able to get in the past single coating Stonhenge using
>either the regular VDB formula, kallitype or palladium. These
>readings are for native kallitye, with no toning.
>
>Printing times to get the first maximum black from a Stouffer Step
>Wedge using this light source (the AmerGraph ULF-28 Continuous Wave
>Xenon) are about the same as for palladium, i.e. about 100 units
>where one unit equals approximately one second. Printing time with
>my bank of BLB tubes was about 300 units, where one unit equals
>approximately one second.
>
>Sandy
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Received on 05/17/06-08:55:45 AM Z