RE: Inkjet negatives and Van Dyke Brownprints

Joe,

I am glad the data proved useful to you and am not surprised that you
had to tweak the values a bit since the original data was calibrated
for printing on pure palladium with just a small bit of potassium
dichromate added to the developer to make clearing easier. When I am
back on my feet I plan to do a more complete calibration test
specific to Classic VDB using a 31 step transmission wedge. I suspect
that the use of more steps will be useful for VDB because of the
rather extreme nature of the blocking we get in the shadows places a
premium on getting the curve exactly right in this area, as your work
appears to confirm.

BTW, the corrected print you posted certainly appears to have an
excellent rendition

About the citric acid pre-soak, and this reply applies to Judy's
comment also, the key to clearing of the ferric salts that cause
stain is in the pH of the wash/soak water. It might well be that the
pH of the water you are using is on the acidic side already, which
would make it ideal for VDB without addition of any acid.
Unfortunately the pH of many water sources is not always the same. I
have tested my own tap water and seen ranges from as low as pH 6.4 to
as high as 7.6. I don't anything about how the water of municipal
water supplies is maintained but whatever they do appears to result
in definite changes in pH from time to time. The use of the citric
acid base serves as protection against these changes.

The other thing that is important to consider is the amount of iron
in the water supply. If this amount is very high it would appear, at
least in theory, that it would be even more important to wash/develop
in a first water bath that is even more acidic than normal.

I hope my comments make some sense. If not please chalk them up to my
present state of stupor resulting from medication I am taking to dull
the rather nasty pain from a knee operation Friday morning. And that
is what keeps me up at this late hour of the morning when I would
otherwise normally be sawing logs.

Sandy

> >>> sanking@clemson.edu 11/19/04 11:26 AM >>>
>>>...
>These values produce very nice prints, with good shadow, mid-tones
>and highlights with both kallitype and pure palladium (for an
>exposure scale of about 1.85, and it also works nicely with VDB....<<
>
>
>
>Sandy,
>
>I tried your neutral curve today and it produced wonderful shadow
>values. The highlights were blocked so I tweaked the curve a bit
>primarily on the low end and presto, a full range VDB with separation on
>both ends of the scale. The negative printed with nice clean highlights
>and good max density. Many thanks for posting the curve info earlier.
>
>I tried the new curve on both my test image full of digital step wedges
>as well as a file I had never used before and both printed quite nicely.
> I'll try to scan the actual VDB prints tomorrow and post them online.
>In the meantime, if anyone is interested in seeing representations of
>the digital files and the final curve and density data, they can be
>found here:
>
>http://my.net-link.net/~jsmigiel/images/technical/vdb_test_11-19-04.jpg
>
>(Be forewarned that the test image is a nude so avoid the page if you
>don't care to view that sort of content or if you are under the age of
>majority. It is also a fairly large jpeg so it may take a minute to
>load if you are on a dial-up connection. I would assume the image may
>look a bit dark and contrasty when viewed on a PC rather than a Mac
>which was used in its creation. However, all the areas of the
>stepwedges show clear separation on the original digital files,
>Pictorico OHP transparency, and final VDB print.)
>
>I also started to use your recommendation of a citric acid bath instead
>of a running water wash at the beginning of the processing steps. I
>don't see as dramatic a shift now as the hypo is used but presumably
>that is because the initial acidified water shifts the tone & color
>closer to its final stage before the acidic hypo solution reacts with
>it.
>
>Thanks again.
>
>Joe
Received on Sat Nov 20 02:37:07 2004