Re: Two methods of sensitizing for Direct Carbon

On Sat, 13 Mar 2004 Grafist@aol.com wrote:

> One. For Direct Carbon which resembles the gum process the sensitizer
> is mixed in with the colloid on coating. Am I correct in assuming that a
> pure gum + pigment coat cannot be sensitized after drying....the gum
> would be washed away by the dichromate? (Judy ??)

They say that John, just like they say a lot of other things. But not so.
You could make the dichromate solution very cold, so that by the time it
started to dissolve the gum it would be done -- before exposure anyway
it's not so serious if you have a little blurring; it dries solid again.

Another way would be to spray the dichromate solution on (as shown in a
couple of articles in the teens), or even (maybe I'm inventing this but it
could probably be done) saturating a mat or paper of some sort & laying it
on.

But what WAS done fairly often was sensitize from the back. I don't
remember if that was done with another sheet or by floating in the
solution or by brushing the solution on from the back (buckle brush) --
probably all. So the answer to your question looks like not so. I'm
having a vague memory now also of something in one of the old books (Photo
Aquatint? One of them...) about a big discovery of applying the gum &
sensitizer separately and finding it was a lot faster, but then in the
next chapter they took it back; it wasn't faster after all.)

But I'd bet one million (no, make that two million) dollars the idea that
it COULDN'T be done was used as rationale for something else.

J.
Received on Sat Mar 13 19:53:57 2004