From: Richard Knoppow (dickburk@ix.netcom.com)
Date: 09/18/01-08:37:28 AM Z
At 09:53 AM 09/18/2001 +0200, you wrote: > > >FB wrote: > >> > >> > The
question is, what other form can selenium be used that >> > does not
contain such high dosage of fixer? Any chemists >> > out there who can
provide an answer? What if we buffer the >> > solution, would it make any
difference? >> > >> >> Sodium sulphide (Na2S) 40g
>> Selenium, red or seleniumdioxide 1g >> water to 1 litre
>> > >..I believe you have to boil this solution to get the selenium into
>solution, at least that is what the T55 formula of Kodak calls for: >(this
is a quote from theweb site:
>http://digipicture.com/anglais/shop/paper01.htm#, I found this formula >in
other sources as well) > >TAKE PROPER PRECAUTIONS WHEN BOILING SELENIUM
POWDER!!!!! > >when you do not have the proper lab equipment and knowledge
about >handeling (and disposing!) dangerous chemicals, you'll be probably
>better of overprinting your POP and tone with much diluted Kodak >Selenium
toner > >Selenium toner bath Kodak T55 formula : > > hot distilled
water: > 700 ml > anhydrous sodium sulfite: >
150 g > selenium ( pulver) : > 6 G > ammonium
chloride : > 190 G > water to make : >
1000 ml > > Add selenium and let boil 30 min.
Filter to >eliminate > the residues, let cool and add
ammonium chloride. > supplement with cold water to
make one liter. > For the use, a volume of this
solution is diluted >with 5 > volumes of water. >
The phototype is immersed lO to 15 min (@ 20°C), >
then washed carefully according to the conditions >
indicated in the preceding lines. > > >Cor > >
My mail reader has made hash of this I am afraid.
Grant Haist quotes the Photo-Lab-Index as stating that T-55 is the same
as KRST, however, from the MSDS I doubt it. The MSDS indicates that KRST
stock is about 25% Ammonium thiosulfate. There is no thiosulfate or
anything which would become thiosulfate in T-55. It is different than other
Selenium toner formulas I've seen in that it does not contain any sulfide.
I looked up the patents given by Grant Haist in his book _Modern
Photographic Processing_ and in C.E.K.Mees _Theory of the Photographic
Process_ Revised edition, for Selenium toner. They may be similar to KRST
but also require long (hours) boiling of elemental selenium. The patent
numbers are:
USP 1,491,313 (1924) and USP 1,499,749 (1924)
Any US patent may be found on the U.S. Patent and Trade-Mark Office site
at: http://www.uspto.gov Those older than about 1975 can be searched by
patent number only and are in FAX TIFF format requiring a plug-in to
display. The best plugin is Alternatiff available off the web as freeware.
Do a Google search to find it.
Off line these can be viewed using the Wang Imaging built into most
versions of Windows. This program was bought by Kodak and is no longer
freeware. I don't know of a good free substitute.
---- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com
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