Adam Kimball (akimball@finebrand.com)
Mon, 18 Jan 1999 13:22:14 -0800
Judy and all,
I think the issue with Newman's method though is that you end up with extra
water in the solution. It seems that most printers (well, many) are trying to
use very saturated solutions of both platinum and ferric oxalate - I know that
is what I strive for.
Every time you add extra water into the emulsion you are effectively lowering
the amount of metal per sqare inch that actually stays on the paper. Using
more sensitizer doesn't work - because the paper only takes so much
(especially rod coated papers). So, if you can absolutely limit the amount of
water by using very saturated metals and iron you theoretically achieve a
coating with a richer emulsion, and ideally you get better blacks because of
it.
Though, one drop isn't going to make a black into a middle grey.
And droppers have there own problems when used to measure minute amount of
chemistry. If drop size can vary 10% per drop (I don't think that is too
unreasonable to assume) and you are using 1 drop- you can have way too much
variability.
I gather the reason that the Chlorate is added to the f.o. directly is for
this reason - no extra water in the mix. Now, if you are doing multiple
coats, the water may actually help, I've heard - though I don't use any.
This is splitting hairs to be certain but Joel's method sounds great to me
because of its ability to add chlorate w/o much water along the way. And not
keeping two f.o around, etc..
I avoid the Chlorate issue by using dichromate in the developer, which has its
own problems of course..
-Adam
Judy Seigel wrote:
> On Mon, 18 Jan 1999, joel lederer wrote:
> > My idea is to eliminate sol. B (ferric oxalate+K. chlorate) and replace
> > it with a concentrated solution of K. chlorate and add this to the
> > sensitizer with a micro pipette (I have seen ones which measure out in
> > 1/100ths of a cc). The plan would be to make a solution strong enough so
> > that the highest contrast could be achieved without "watering" the
> > mixture down too much and not so strong that I loose the ability to
> > measure small amounts when a slight increase in contrast is needed.
> > Ultimately I would like to use a solution in which 1/10th of a cc would
> > be the highest contrast (for a 4x5 print) and 1/100th of a cc would be
> > the lowest contrast. For larger prints the amount could be multiplied.
> > I'm not sure where to begin with these experiments and have thought of
> > some questions. Perhaps I'm missing something obvious.., but here goes.
>
> Joel, I don't know any of the fine points of pl/pd (or the medium points
> either, for that matter). But it seems to me what you're suggesting is
> very much like the method Alan Newman devised & taught 20 years ago &
> which was the way I was taught, a method which has always seemed to me
> more convenient than the "traditional."
>
> I don't recall the k chlorate concentration, but you mixed it up
> separately (probably 15%, I'll look it up if no one else has it) and add
> by drops to your mix at mixing time. It has the great advantage also in
> that for a very small amount you can cut a drop with a drop of distilled
> water before adding. The straight K chlorate certainly kept for the
> period during which I used it.... say 6 months ... and I daresay keeps
> still in the back of a shelf somewhere...
>
> cheers,
>
> Judy
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