Re: Any Process that Uses Positives


Wayde Allen (wallen@boulder.nist.gov)
Mon, 07 Jun 1999 10:50:11 -0600 (MDT)


On Fri, 4 Jun 1999 FotoDave@aol.com wrote:

> Is there any relatively simple process that uses positives instead of
> negatives? Judging from all the discussions on making enlarged negatives,
> there probably isn't a simple one, but I thought I would ask.

A few weeks ago I made a sheet of white pigmented gelatin for carbon
printing. I've so far made one test print from a Lith film positive, and
it seemed to work OK. The resulting image is nice, but not as brilliant
as the usual black pigment on a white paper base. It looks like the
problem is in keeping the whites white. Besides dichromate staining of
the pigmented gelatin, you need to get a pigmented layer with enough
opacity to cover up the black of the base paper. It is also more
difficult to find a black substrate to print on.

I used a piece of exposed, developed, and fixed photographic paper as my
final support. The result looks somewhat like a tintype although with
the relief pattern of the carbon print.

Other positive processes:

   Daguerreotype
   Ambrotype
   Tintype

I also seem to remember reading in Crawford's book (keepers of Light)
about a cyanotype recipe that uses a positive. You might want to check it
out.

- Wayde
  (wallen@boulder.nist.gov)



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