RE: Pure Pt printing and solarazation

Hi Marek,

In short (don't try this if you do not have professional equipment, a good fumehood en knowledge about chemistry and safety)

I soluted Pt wire in Aqua Regia (takes a loooong time) to make H2PtCl6, neutralised carefuly with Pot Carbonate to produce K2PtCl6 (and a lot of KCl and KNO3, tried to wash it away with cold water, was partially succesfull). The precipttted K2PtCl6 was reduced by an equimolar amount of PotassiumOxalate. I took care to leave some K2PtCl6 on the bottom, to make sure that the reaction would not go to far and produce Pt. The resulting solution (after filtering of K2PtCl6) grew very nice red needles of K2PtCl4, the solution stayed ruby red. I poured of this solution which still roughly contained 50% of the yield plus the KCL and KNO3.

I used the dried red crystals as my Pt material (and saved the rest ofcourse). If I understand it correctly these red crystals from the first crysalisation should be very pure. After soluting (20grams in 100ml water) I see no black precipitate which would be Pt, nor a yellow precipitate, which would be K2PtCl6.

Mmmm not so short after all. If there would be a next time I'll approach it differently though.

Perhaps there is still KCl and KNO3 in my Pt prep (how to test it?), would it influence the Pt printing?

Best,

Cor

> -----Original Message-----
> From: Marek Matusz [mailto:marekmatusz@hotmail.com]
> Sent: donderdag 1 december 2005 15:24
> To: alt-photo-process-l@sask.usask.ca
> Subject: RE: Pure Pt printing and solarazation
>
>
> Cor,
> How did you make your platinum salt? If it was made by
> reduction of the
> Pt(IV) salt it is possible that you might have some unreduced
> platinum left
> in the solution. It would act as a contrast booster, similar
> to Na2PtCL6
> method used to adjust palladium print contrast. Longer
> exposure time would
> be consistent I think. I have not printed pure Pt, so I am
> not sure how it
> behaves.
> Marek
>
>
> >From: "Breukel, C. (HKG)" <C.Breukel@lumc.nl>
> >Reply-To: alt-photo-process-l@sask.usask.ca
> >To: "Alt-Photo-Process-L (E-mail)"
> <alt-photo-process-l@sask.usask.ca>
> >Subject: Pure Pt printing and solarazation
> >Date: Thu, 01 Dec 2005 10:09:45 +0100
> >
> >Hi,
> >
> >I recently entered the world of pure Pt printing..(caveat: I
> "made" my own
> >K2PtCl4, which is AFAIK quite pure, but I am not 100% sure
> about it, do not
> >have the means to test for impurities)..and as expected: it
> isn't a easy
> >world..;-)..
> >
> >I have tried a few things: Pt & FerricOxalte, Pot.Oxalate as
> developer, and
> >Extravagatype: Pt & AmmoniumFerricOxalate, developed in 1:1
> >glycerol/PotOxalate with a foambrush, both were dried "bone
> dry" with a
> >hairdrier at medium heat (RH in my place around 70%, temp 16degC).
> >
> >Paper: Simili Japon
> >Chemistry: 200 ul K2PtCl4 (say around 4 drops)
> > 200 ul 25% FerricOxalate
> >Negative: 4*5, processed in PyrocatHD
> > Stouffer Stepwedge
> >
> >I observe the following with both approaches:
> >
> >long printing times: about 1-1.5 stops longer compaired with
> a Ziatype
> >(both with a Stouffer stepwedge and a 4*5 neg), which means
> printing times
> >in the range of 25-35 min! (versus a Zia around 9-11
> minutes) with my set
> >up.
> >
> >Reversal/solarization of the deepest blacks & border : they
> turn in a
> >ligther brown versus a a deep brown/black in the detailed
> shadow area.
> >
> >Overal image tone is black brown, the Extravagatype beeing a
> deeper black.
> >
> >I can think of the following things to explain the
> solarization: Stiil too
> >humid? Too little metal? (I can not load more in one coat,
> this amount is
> >already on the edge, the metal solution seems to be at it's
> saturation
> >point, at room temperature it's ok, at 16deC (my darkroom in
> winter time)
> >there are nice red crystals precipitated). Too long a
> printing time? Don't
> >know what to do about that (btw I cool my UV bank with fans).
> >
> >I also tried some Ziatyp with Pt: I used 30 ul Pt, 90 ul
> Cs2PdCl4 and 120
> >ul AFO, dried very quick, printed very humid (with a piece
> of saran wraap
> >to protect the negative. I obtained a nice print, neutral
> grey of tone,
> >nice midtone separation, a bit lower Dmax compaired with the
> Pt print.
> >
> >But the most striking (but not surprising) thing was the
> hughe difference
> >in tonal values. The pure Pt print has almost blocked up
> shadows, and could
> >use some more density in the highlights, wheras the Ziatype
> had very open
> >shadows, good density in the midtones, and a tad to heavy in the
> >highlights. I guess this demonstrates the effect of self
> masking in POP
> >quite nicely. To repeat: I used the same neg for both
> prints: for the pure
> >Pt this neg is too heavy (too much contrast in the print),
> whereas for the
> >Ziatype the neg could use some more density (although this is easily
> >"cured" by adding a litle bit of amm. dichromate).
> >
> >Comments and advice appreciated!
> >
> >Best,
> >
> >Cor
> >
>
>
>
Received on Thu Dec 1 08:47:15 2005