RE: More questions - KAuCl2 vs AuCl3 - it's KAuCl4

Ok, it seems that the compound I use is anhydrous KAuCl4... The gold seller
told me 1.92 gr of this compound has 1 gr pure gold and when you check this
figure against anhydrous KAuCl4, they match each other. I just finished
toning an Argyrotype with fresh thiourea-gold toner and it tones to
completion in about 1 minute (completion is: no further color change and/or
considerable slowing of color change).

BTW, palladium toning is gone forever for me; the gold toned print is just
as I want it (in terms of contrast, color and dmax). Palladium toned print
looks anemic when compared to the gold toned print (thioure-gold that is).
Will send scans of three prints (untoned, palladium toned & gold toned)
later, when the prints are dry.

Regards,
Loris.

-----Original Message-----
From: Loris Medici [mailto:mail@loris.medici.name]
Sent: 20 Mayıs 2006 Cumartesi 17:18
To: alt-photo-process-l@usask.ca
Subject: RE: More questions - KAuCl2 vs AuCl3

Sorry Alberto, can't provide you any comparison info because I never used
AuCl3 (impossible to find locally and have to order quite alot - over my
budget - for having it imported). The formula I provided may not be correct
since I just learned - from someone posting off-list - that KAuCl2 will
decompose in contact with water and precipitate gold (something that the
compound I use doesn't do). The formula is more likely to be something like
KAuCl4.xH2O. Will pay a visit to Grand Bazaar and learn the exact formula.

Regards,
Loris.

-----Original Message-----
From: Alberto Novo [mailto:alt_list@albertonovo.it]
Sent: 20 Mayıs 2006 Cumartesi 08:53
To: alt-photo-process-L@usask.ca
Subject: Re: More questions - KAuCl2 vs AuCl3

Loris,
did you note anything different between Au(I) and Au(III) toned prints (hue,
speed, etc.)?
 From a theoretical point of view, though the m.w. is almost the same, the
substitution of Ag by Au is three times more efficient when using Au(I)
solutions.

Alberto

> A note about gold chloride (AuCl3): one can also use KAuCl2 (which is
> used in gold plating industry, AFAIK) perfectly for gold toners. For
> me (a person located in Istanbul) KAuCl2 is cheaper and easier to find
> (just a short visit to the gold sellers in Grand Bazaar). I use the
> thiourea-gold formula replacing AuCl3 with KAuCl2. The gold percentage
> difference is extremely small (AuCl3 -> 64.94% vs KAuCl2 -> 64.16%),
> therefore you can substitute
> AuCl3 with KAuCl2 using the exact amounts stated in the formula.
>
> Just my 2 cents,
> Loris.
Received on 05/20/06-12:09:18 PM Z