Re: Albumen sensitiser question

[eric nelson <emanphoto@gmail.com>]

I wouldn't know if there are crystals at the bottom of my agno3 as there is a layer of kaolin at the bottom.  You will need that too if floating your sheets on the agno3 surface to sensitize.  This is because the organic materials in the paper and albumen will darken the solution over time and lower it's effectiveness.  After the solution begins to darken, shake the bottle and let the kaolin settle overnight taking the discoloration with it.  Reilly has a historical illustration of how to set up a siphon for that and mine is nearly identical except that I used a glass milk bottle. :)

When you say James, do you mean Reilly?  

Since it takes 2-3 minutes of floating the paper on the agno3 solution to properly sensitize albumen, brush or rod coating would be a very uneven coating.  I tried brush coating only once with inferior results UNLESS one wants that kind of look, which could be cool.  But for straight printing/imaging floating gives the best results.

Eric

On Sun, Feb 1, 2009 at 4:54 PM, John Brewer <john@johnbrewerphotography.com> wrote:

Hi folks

 

I made up some silver nitrate sensitiser according to James p 471, that is 15% silver nitrate plus 5% citric acid in distilled water.

I see there is now some crystals at the bottom of the bottle. They weren't there when I made the solution up and sensitised some paper. I can't seem to dissolve them, even with heat and vigorous shaking. What are they? Are they anything to worry about? Can I filter or decant them out?

 

One other thing, James says that coating with a rod is possible. This would be preferable for me at this moment. As the sensitiser is clear, coating under safelights is tricky to say the least. Can I do it under low ambient light as I do quite safely with gum? If not any tips or tricks would be most welcome.

 

Thanks,

 

John.