From: Richard Knoppow (dickburk@ix.netcom.com)
Date: 08/23/02-01:19:08 PM Z
At 01:28 PM 08/23/2002 -0400, you wrote:
>>"How much and how long?"
>>The article does not say. I had always done the whole process in a room
>>with pretty good light. The issue came up because I directed the process to
>>someone who had no luck with it and he wrote to the PMK newsgroup and Mr.
>>Gainer clarified that the light exposure is necessary, but apparently the
>>intensity and duration were not specified. I find that just working in a
>>brightly lit room works fine. Others have just held the negatives up to a
>>bright incandescent light for a few seconds with good results.
>>
>>----- Original Message -----
>>From: <ARTHURWG@aol.com>
>>To: <alt-photo-process-l@sask.usask.ca>
>>Sent: Friday, August 23, 2002 9:50 AM
>>Subject: Re: negative intensification
>>
>>
>>> How much bright light, and for how long? Arthur
>>>
>
>Do you then redevelop in the dark or continue in room light?
>Thanks.
>tillman
>
You continue in the light. Some intensification processes work by
converting the image silver back to a silver halide. If the halide is
redeveloped in a normal developer it must be fogged either by exposure to
fairly strong light or by a chemical fogging agent. The amount of light is
whatever is necessary to create development centers in all of the halide.
Reversal processing, which is similar, typically requires re-exposure to
something like a 100 watt bulb in a small reflector for a minute or so.
Both sides of the film should be exposed. Some reversal processes
recommended a 500 watt photo flood.
The exposure must not be so much as to generate photolytic silver so
direct sunlight is to be avoided.
If sodium sulide is used to redevelop no light fogging is needed since
the sulfide will convert unexposed halide. However you will have a sepia
image.
There are a number of intensifiers. Some increase overall density without
much effect on contrast, some mainly increase contrast. None will
compensate for exposures which ar so low that no silver was produced in the
original development. In other words, you can not intensify an image which
does not exist.
Bleach and re-developing can also be used to lower the density or
contrast by using a less active developer and not allowing all the
rehalogenated silver to redevelop. The negatives should be fixed after this
last process since some halide will be left.
Actually, its a good idea to refix negatives which have been intensified
by redevelopment since some small residue of halide may be left. This is
not necessary when sulfide is used and probably not when a fogging agent is
used.
Staining developers, like Pyro, are inherently intensifiers. The stain
image is equivalent to intensification.
Pyro redevelopment, Selenium toning, and Silver intensifiers produce
permanent images. Chromium is less permanent and Mercury intensifiers are
even less permanent.
Kodak published a Quinone-Thiosulfate intensifier (Kodak In-6) which it
claims produces the highest degree of intensification of any known formula.
The image is not entirely permenent and, I suspect, the process is probably
not to predictable. I will post the formula and instructions to the list if
its wanted but I am not proposing it as a practical method for alt
processes negatives.
---- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com
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