Showcase for Your HCWP's

[fgorga]

Just an FYI regarding paper for Van Dyke Brown printing...

In his book Kallitype, Vandyke Brown and Argyrotype, Don Nelson has a table of 42 papers suitable for VDB printing, only two of these papers require acid pre-treatment before coating.

 

[Raghu Kuvempunagar]

Just an FYI regarding paper for Van Dyke Brown printing...

In his book Kallitype, Vandyke Brown and Argyrotype, Don Nelson has a table of 42 papers suitable for VDB printing, only two of these papers require acid pre-treatment before coating.

Just curious, has this got something to do with the fact that VDB is FAC based whereas the other two processes are not (i.e. citrate vs oxalate)?

Interestingly, Legion Revere Platinum 300 gsm, though a paper made for alt processes and doesn't have buffer, gives better DMax when treated with Sulfamic for all three processes including VDB according to the book.

 

[glbeas]

Is this a soak in a tray of dilute acid or can it be applied like the sensitizer and let dry?

 

[fgorga]

Just curious, has this got something to do with the fact that VDB is FAC based whereas the other two processes are not (i.e. citrate vs oxalate)?

I do not know the answer to this question.

Interestingly, Legion Revere Platinum 300 gsm, though a paper made for alt processes and doesn't have buffer, gives better DMax when treated with Sulfamic for all three processes including VDB according to the book.

My thoughts... even a paper lacking calcium carbonate contains additives (whose identity is proprietary information). Some of these additives might be washed out of the paper upon soaking just in water, especially hot water. Additives, other than carbonate, might also react with acids.

There is no way of knowing what might be going on since we do not know anything about the specific compounds involved.

Just another example where empirical knowledge (aka experiments) play a large role in alternative process printing.

 

[fgorga]

Is this a soak in a tray of dilute acid or can it be applied like the sensitizer and let dry?

Removing carbonate buffer with dilute acid is generally (universally? I don't know anyone who does otherwise) done in a tray followed by washing in water to remove excess acid and the products of neutralization.

Personally, the only exception I make for this is when I treat paper for salt printing with citric acid. I include citric acid in my sensitizer so I just briefly rinse the paper after removing from the citric acid tray. I figure that a little extra citric acid / citrate doesn't make a difference.

My bottom line, these days, is that I use either HPR or Revere Pt for the large majority of my salted-paper or Pt/Pd printing. I don't bother messing with other papers that need acid pre-treatment except if I need/want a special look (most often a warm white paper) for a print. Life is too short.

The exception to the above is cyanotype. In this case I never acid pre-treat any paper. Rather, I 'develop' cyanotypes in a tray of 10-15% vinegar for several minutes before washing them with water. My guess is the the vinegar neutralizes the carbonate before there is significant hydrolysis of the Prussian blue.