RE: VDB

Hi Judy. First of all thanks for the suggestions.

I guess good Dmax is a little bit subjective concept. Coming from silver
gelatine printing (and quadtone b&w inkjet printing), the max. density I get
with alt-process prints looks always weak to my eyes.

I use the formula given in Wynn White's article @ unblinkingeye.com
(http://unblinkingeye.com/Articles/Vandyke/vandyke.html). Formula says:

Solution A
Ferric Ammonium Citrate 9.0 gm
Distilled Water 33.0 ml

Solution B
Tartaric Acid 1.5 gm
Distilled Water 33.0 ml

Solution C
Silver Nitrate 3.8 gm
Distilled Water 33.0 ml

My chemicals are all good. My scales are all good (no problems with Ziatype,
Cyanotype). My silver nitrate is white, it shows no precipitation and/or
cloudyness when mixed with the distilled/deionized water I use. I use a dark
amber coloured container with plastic caps (double caps). I use dedicated
brush and plastic pipette for measuring coating solution and for
application. Paper comes from its original packaging, no problems with other
processes. No extra sizing (it's Cot 320; extremely good sizing on the front
side). I know there are people printing platinum on that paper (another
process that doesn't like gelatine sizing) so I guess its sizing is
syntethic (aquapel?). I wash in 1% citric acid (in order to get rid of all
unexposed sensitizer), I use plain 2% sodium thiosulfate fixer (no other
chemicals added). Fixing time is 1 min. I expose right after drying the
paper (5mins flat, then 25mins cold air fan).

I get good Dmax by double coating and toning in gold before fixing. Never
got good Dmax by single coating.

Regards,
Loris.

-----Original Message-----
From: Judy Seigel [mailto:jseigel@panix.com]
Sent: 16 Ekim 2005 Pazar 08:11

To: alt-photo-process-l@sask.usask.ca
Subject: RE: VDB

On Thu, 13 Oct 2005, Loris Medici wrote:

> I'm sure I can't get even close to 1.2 with one coat VDB (subjective
> comment: didn't measure, don't have a densitometer). Your 1.5 is very
> close to semi-matte RC paper max. density (which is around 1.6
> IIRC)... If I were getting such density I'd never bother with double
> coating. I have Stonehenge paper sitting somewhere, will try it for VDB
when I will have time...

I'm puzzled by the reports about insufficient VDB density... also emulsion
ruination... I've used single coat VDB emulsion aged nearly 2 years, plated
out in the bottle, full of black precipitate, etc. etc.
without problems and with good d-max.

Wondering about:

Is it possible a weaker formula circulates? What formula are folks using?

Are all chemicals known to be good?

Do you trust your scale? (That's a relatively small amount of silver
nitrate, so truth in weighing matters.) Is the silver nitrate still white?

And the water: We had a problem when the silver precipitated out as soon as
it was added to the water, BEFORE combining with the other solutions.
The hardware store had sold us tap water in a "distilled" water container.
(On a hunch I brought it to the chem dep't which confirmed.)

(I note that I was mixing the silver solution in a babyfood jar with a metal
cap... When it precipitated right out, I thought it was the cap. I suppose
the cap didn't help, but it was the water.)

Are you sure your container is light tight? Not all colored plastic is.
(I kept the brown glass bottle, with black plastic cap, in a dark closet
when not in use.)

Are you using a *dedicated* applicator -- say, foam brush that doesn't go
into anything else?

Does the paper lie on a *clean* surface for coating? (If stroke extends
over the edge & onto a dirty surface, it picks up stuff.)

Are you gelatin sizing? VDB does NOT like gelatin size.

And fixer -- I found that two minutes in a plain fix of (percent I'd have to
look up, but much weaker than standard fix) was the longest and strongest
you could use without bleaching. (I probably have it somewhere, probably in
P-F, but it made an enormous difference.)

Also, I mention what maybe most folks know, but the books seem to have wrong
-- The first rinse, in plain water, before fixing, should not be just "until
the water runs clear." A student did a variables test and found a much
brighter deeper print with a 5 minute rinse before fixing.

Heat drying the emulsion kills D-max, but storage before exposure and before
development can also cut densitity. And probably more variables I'm not
thinking of now...

cheers,

Judy
Received on Sun Oct 16 05:58:05 2005