> The Vandyke Brownprint process seems to be one of the easiest alternative
> printing processes. However, in spite of the large number of available
cut=============
> One of the difficulties I've encountered is paper choice. Some papers just
> don't work well with Vandyke. Cranes Kid Finish works well, while Cranes
> Resume does not.
Sam, we found that when we STOPPED HEAT DRYING Vandyke brown, just letting
the emulsion air dry, almost every paper seemed to work -- and all D-max
was richer...
> The biggest problem that no one else seems to have noticed, however, is the
> way the solution ages, along with the precipitation of the silver in the
> solution, affects the image. After intitial testings, I've found these
> differences between freshly mixed Vandyke solution and ones several day old:
I think there is a "ripening" process that lasts about a week. After that
the emulsion seems quite stable... I've used it four years old, with no
noticeable change, although I did NOT do a comparison test, so I probably
shouldn't say that...
> >From freshly mixed solutions:
> 1/ The printed out image appears more yellow-orange, where the one from
> not-freshly mixed solution darker and less lively.
> 2/ During the initial rinse, the color is a richer, more chocolaty brown
> compared to the more ochre brown from the older solution.
> 3/ After it's dried, the color turns to a deeper, more lively, and cooler
> brown, with a longer tonal range, with steps 2 to 16 on the 21 step-tablet
> visible. The print from the older solution shows only steps 3 through 14,
> and in a lighter, less intense warmer brown.
Bob Schramm found that after a couple of weeks distinct differences in
print color from different formulas were much less so... I haven't found
any particular correlation between "print out" color & final print color.
My *guess* would be that the way the solution ages is also a factor of the
state of the ferric ammonium citrate you began with -- it is, to quote
Mike Ware, an "ill-characterized" whatever. I find that both cyanotype &
VDB will act differently in different batches of the identical formula. I
attribute that to different characterizations of fe am cit. (The only
ingredient that changed -- I have a lifetime supply of silver nitrate and
tartaric acid.)
> My guess is that the differences are caused by the silver precipitating out
> of the solution. Less silver, less dark.
In my experience there's usually some metallic plating out on the sides of
the bottle, and the dropper, but I haven't noticed any concomittant
lightening of the print.
> Problem is, silver sometimes precipitate as white particles, and
> sometimes dark particles. My hunch... tells me that the white is
> undissolved silver, that can be dissolved, according to Dick Sullivan,
> by adding more tartaric acid to the mix. The black particles are
> obviously metallic silver, which is best filtered out before use. Am I
> right?
It didn't used to happen, but now it does (maybe the fe am cit) that after
6 months or so when you take an eyedropper of emulsion you see black
specks in it. But when you spread the emulsion on the paper, they
disappear, or reabsorb. I've never filtered and never seen specks in the
final print.
>.....I'm
> stocking the ingredients in separate bottles, and mix them only on the day
> of use.
Sam, I'd worry about that... my chemistry degree is, um, from
kindergarten, but somehow I think (aside from being more trouble) the
solutions probably keep better mixed.... Anybody?
> Sorry about the length of this message. Hopefully it's not going over the
> same grounds as available in the archives.
I don't recall anything on the topic.... now we need some more answers...
Hello?
cheers,
Judy