[Alt-photo] Re: drop count in pt/pd

[Loris Medici]

Hi Christina,

Same here, I was counting drops, then I noticed how big the LiPd drops are
compared to AFO drops and then realized I may be wasting precious Pd. (Then
it was much much precious to me than it is now, because at that time I had
to import Pd solutions from the States and Turkish customs is notoriously
strict and problematic about chemistry. Picking chemistry from the customs
/ post office was always an adrenaline rush.Then a couple of years ago, I
found someone that could make me PdCl2 here in Istanbul. Phew, what a
relief!)

As you figured out, it doesn't matter if you're using the drop counting
method or syringes, as long as the solution *strengths AND volumes* are
well balanced. I continued to the drop count method (by testing how much
drops is 2ml of each solution) until I purchased a NuArc 26-1KS and started
to print images that were 16" wide. Eventually, the required solution
amounts made me go nuts while trying to count so many drops and switched to
syringes permanently. Like to count them too, but not so many! :)

Regards,
Loris.


2013/11/6 Christina Anderson <christinazanderson at gmail.com>

> Loris,
> You are absolutely right; I had not decided to "go there" in this
> discussion. But when I was having all that bleeding a couple years back I
> was looking at my drop count and realized how much bigger the pd drops were
> in comparison to the ferric drops. Plus my pd solution (which I made from
> scratch with pd from Engelhard, now Basf I think) was really rich dark
> brown compared to other solutions I have looked at since that seem a bit
> less chocolate and more yellow. I realized that I was maybe wasting metal.
>
> I filed this in the back of my brain until Mark Nelson and I were talking
> one day and he brought this up that he uses a 961 mix because of the
> smaller drop size.
>
> It goes against the old books that always talked about putting a couple
> extra drops of metal in the mix for good measure, so that is also why I
> didn't mention it, but it really is a waste of metal, I would think.
>
> I'm not a chemist so I don't know what is happening at the chemical level
> with too little ferric but the same is true (or maybe it is COMPLETELY
> unrelated but a similar concept) when I was doing 2  20% FAC to 1 8%
> potassium ferricyanide in cyanotype and getting grainy results and white
> specks and bleeding. Since I have gone back to 1:1 those problems are
> solved. That was courtesy of Alberto Novo.
>
> You even use about 8 drops more solution than I do for that same coating
> area, if, in fact, the area was 8.5x11 (not 8x10). I would use 47 but of
> course that is silly because if I do a 661 it'd be 52, a 961 48.
>
> Haven't used the pipettes yet, though I have a couple, but I imagine they
> would be much more accurate than drop counts. I must love counting out
> those drops :)
> Chris
>
>
> Christina Z. Anderson
> http://christinaZanderson.com/
>
> On Nov 6, 2013, at 2:13 AM, Loris Medici wrote:
>
> > Hi Catherine,
> >
> > If possible, measure the amnt. of solution by milliliters using thin
> > syringes with 0.1ml resolution (using separated / dedicated syringes for
> > each solution)... The properties of each solutions differ, consequently
> > their drop sizes also differ (sometimes considerably!), therefore the
> drop
> > count may not be 100% reliable. (You need equal amounts of iron and noble
> > metal solution for optimum results...)
> >
> > As for coating volume; my standard is 0.025ml per sq. in., some papers
> need
> > a little less than that, some a little more. For 8 1/2 x 11" coating
> area,
> > my standard would translate to ~2.3 - 2.4ml total volume. (Which is
> around
> > 55-60 drops (of water!) with my cheap plastic pipettes - very close to
> > Christina's count, but only for water and solutions close to water; it's
> > not the same for 25% AFC for instance...)
> >
> > ​Regards,
> > Loris.​
>