From: Christina Z. Anderson (zphoto@montana.net)
Date: 09/08/01-02:44:18 PM Z
2%, or 2 g. to 100ml water and 1 g. = 1/4 tsp. 1 drop = 1 grain and 20
drops are = 1 ml. Please correct me here if my math is wrong. But that
would, then, be 1/2 ml of this stuff per 30 ml gelatin.
Photographer's Formulary sells a hardener with their Formulite brand VC
liquid emulsion and has all their use of their emulsion online at
www.photoformulary.com . I have used this for hardening. You use very
little of it, and can use it in the gelatin, emulsion, or the developer. In
the emulsion you only mix it 1:20 first hardener to water and then 1:20
hardener working solution to emulsion, so the bottle of stuff goes a hugely
long way and will outlast your emulsion bottle for sure if you are only
using it in that. They have an MSDS sheet available but I cannot get a hold
of them today because it is saturday and thus I know it is formaldehyde free
but do not know if it is chrome alum or what and if it can substitute
directly for the proportions I have said here. Well now, THAT was a run-on
sentence for sure!!
Reed and Jones in Silver Gelatin book use a little dif measurements:
20 ml of the 2% solution to 5 g gelatin and 980 ml hot distilled water .
This is a tad less gelatin and a tad more chrome alum. They say that chrome
alum, as opposed to formaldehyde, is less toxic and less likely to fog
emulsion. This alum hardener is sold by Silverprint (Luminos here in the
states?) called Silverprint Subbing Solution and Emulsion Hardener, 5 packs
of stuff that each make 100ml of stock solution. This is used 7ml to 250 ml
liquid emulsion, and is also used in the gelatin subbing.
Of course, glass can also be subbed with clear varnish, oil based.
Chris
>
>
> On Fri, 7 Sep 2001, Christina Z. Anderson wrote:
> > Ceramics, as well as glass, need cleaning and subbing or the stuff
will
> > slough right off. Sub both with a hardened gelatin coat. Fabric needs
no
> > prep. Method of subbing glass: first, do not clean glass with soap
with
> > this method, as it may leave a film deposit. Clean it with sodium
> > carbonate--sal soda, washing soda, Arm and Hammer. Let it dry. Then,
take
> > 1 teaspoon of Knox gelatin per pint of water, and sprinkle it in cold
water
> > and let it stand for 15 minutes until dissolved. Heat gently on the
stove
> > until melted. Add 10 drops of chrome alum to each ounce (30 cc) of this
> > solution, and pour the hot solution onto the glass. Allow to dry 4
hours or
> > overnight.
>
>
> 10 drops of what % chrome alum ???
>
> J.
>
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