Re: Lead Toning Cyanotypes - share your experience please

From: Loris Medici <mail@loris.medici.name>
Subject: Lead Toning Cyanotypes - share your experience please
Date: Wed, 23 Aug 2006 15:31:07 +0300

> 1) What are the dangers associated with Lead(II) Acetate Trihydrate?
> It looks like moist sugar/rock salt, it seems it's deliquescent and
> I suspect it's a hard-to clean, sticky matter (see below for more
> detail)... Does Lead(II) Acetat evaporates at normal room
> temperature? What I can do to thoroughly clean my trays from it?

I would use all protective measures in laboratory. I wouldn't dump
lead solution down the drain.

> 2) I've mixed a 5% solution with "tap water". The chemical seems to
> not going into solution well; the solution gets cloudy and you can
> see very very fine particles playing on top of the print when you're
> toning, and most importantly this solid precipitates on the print
> surface. Is it OK to make a toning solution with tap water or should
> I use distilled water?

You should be able to dissolve 4-5% at room temperature, but 5% is
about the solubility limit. I can think of two sparingly soluble or
only very slightly soluble lead compounds: lead carbonate and lead
halides. I'd use distilled water, boil and cool before use, if absence
of those cloudy matter is essential. If insoluble matters still form,
it's most likely due to impurities in the chemical stock (especially
if it's technical grade lead acetate).

> 3) I noticed the precipitation while drying the print - the dark
> tones were showing a white veiling which goes off when you rub a
> paper towel to the print. I concluded that it's precipitated
> Lead(II) Acetate and quickly got rid of the print. I touched the
> dried prints with bare hands (but toned using latex gloves) - will I
> die!? ;)

I would wash it off thoroughly with soap and try to avoid the future
exposure.

> * In short, how should I use this toner without causing any health
> risk and damage to myself and the viewers/customers/environment?

I would recommend to avoid lead compounds altogether.

Very small amounts of lead compounds are useful dopants in silver
halide emulsions (a trace amount of impurity that is deliberately
added to a specific part of the crystal to increase light sensitivity)
but I don't like to handle them in my darkroom, even though they are
very tiny amonts, so I had to seek alternative compounds.

The regulation on lead in the US is rather strict. But it should be.
Received on 08/23/06-07:51:50 AM Z