Dmax of VD prints

[Sandy King <sanking@clemson.edu>]

Keith Gerling wrote:

>
>
>>If you're not getting good D-max, you may be...
>
>>heat drying (lowers D-max, on some papers blows it right out)
>
>>not coating properly (ie, not wetting paper enough)
>
>>using stupid paper
>
>>adding gelatin size to paper
>
>>adding some cockamamie ingredient, like gum arabic, to emulsion
>
>>having bad chemicals
>
>>not using distilled for emulsion
>
>>fixing too long (2 minutes absolute MAXIMUM, after which fixer bleaches)
>
>>or fixer too strong, try 26 g am thio to (is it a litre? this from memory)
>>water
>
>>or possibly not washing ENOUGH in the water before putting in fixer. Do a
>>time test... Sometimes with thicker paper this first wash has to be longer
>>than 5 minutes...
>
>Nope on all of the above, except possibly the last one. But now I am 
>curious as to how a
>really good Van Dyke compares to a really good kallitype, and am interested
>in hearing from anybody who has had success with both processes.
>

A really good VD compares favorably to any process, including 
kallitype, provided you like to limited range of tones available. As 
far as Dmax goes, it is certainly possible to get as great with VD 
with traditional kallitype.

If you are not getting good Dmax with VD *something* is wrong with 
your procedures. Assuming you are doing all the things above right 
that Judy mentioned, perhaps the problem might be the negative. I say 
this because as you know, the one outstanding difference between VD 
and kallitype is that the former is a POP process, the latter is DOP. 
With a DOP process you can always get a good Dmax (at least as much 
as the process/paper will allow) by simply exposing long enough. If 
your negative is not of the right contrast for the process you may 
have a tonal scale that is too short or too long, but you can always 
get the maximum Dmax through the exposure.

On the other hand, with a POP process you will not be able to get a 
good Dmax with a negative that does not have a DR that matches the 
tonal range of the process. (This varies according to process. For 
example, with salted paper the ideal DR for the negative is about 
1.8-2.2. With VD the ideal DR is about 1.4-1.6.) With POP there is a 
self-masking feature; the longer you expose, the flatter your print 
becomes. They key with any POP process is that Dmax should occur in 
the deepest shadow in the same time it takes to reach textured detail 
in the highlights. The worst scenario for POP is to have a negative 
with a very high shadow value, say 0.40-0.60 and a relatively low DR, 
say 1.1 or less. With VD, if you expose such a negative for too short 
a time you will not have any texture in the highlights, whereas 
excessive exposure will result in a print that is unacceptably flat.

So, if you are doing everything else right and still getting 
unacceptable Dmax you might want to measure your negatives to see 
what kind of DR you are working with.

BTW, I hope this message does not offend. My email system (Eudora 
5.1) suggested that because I used the word "D..e" six times in the 
text there was a high probability that the message would offend 
someone!! I quote from the warning, "your message is the sort of 
thing that may get your keyboard washed out with soap, if you get my 
drift." And it highlighted the message with three large red peppers. 
So I changed to VD and it let me send. The marvels of PC talk!!

Sandy King


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