[pure-silver] Re: multigrade paper is amazing
- From: Claudio Bonavolta <claudio@xxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Sat, 10 Nov 2007 13:21:32 +0100
Dave V a écrit :
Sorry Richard, Your question and Shannon's are completely different.
Your is "How" and Shannon's is "Wow"!
Regarding Richards question. I like to keep answers simple. You can
get there many ways. The order suggests history of sophistication.
Here's three or four.
1. Make a high contrast, blue sensitive emulsion and coat it. Make a
slower blue sensitive emulsion and coat the grains in the kettle with
a low contrast green dye. Coat this on top of the blue emulsion.
Phase two > use laminar flow coating and coat at the same time with
thin layers.
2. Make the same emulsions as above in two different kettles. Mix
them together and coat them in one layer.
3. Make a big batch of high contrast blue emulsion and add just enough
low contrast green dye to the kettle to coat half (or some other
ratio) of the blue crystals but not all of them. This is called
'starved' sensitization. Coat this in one emulsion.
Note: You can not take a high contrast blue emulsion, sensitize it
with a low contrast green dye and get a variable contrast system. You
get what ever contrast you sensitized it to with the green dye.
That's how you get graded papers.
<snip>
Dave
Thanks Dave but just to be sure I understood it fully ...
By "coat the grains in the kettle with a low contrast green dye" does is
mean you coat the surface of each crystal with a green dye before
putting it in the emulsion, like putting a micro green filter in front
of every grains ?
--
Claudio Bonavolta
http://www.bonavolta.ch
=============================================================================================================
To unsubscribe from this list, go to www.freelists.org and logon to your
account (the same e-mail address and password you set-up when you subscribed,)
and unsubscribe from there.
Other related posts:
