U of S | Mailing List Archive | alt-photo-process-l | Re: Gum over Cyanotypes

Re: Gum over Cyanotypes

Hi Judy,

28 Nisan 2009, Salı, 11:56 pm tarihinde, Judy Seigel yazmış:
> ...
> I agree. My experience is that cyano is better without a pre-size.
> (And that's apparently Sarah's experience too.)
> When I began cyano, I tried every size I ever heard of & found that
> starch, gelatin (with or without hardener), spray, glue, whatever, all
> made an inferior print. At the time most sources did seem to call for size
> (tho in those early books, "info" tended to be cut & pasted from earlier
> books, rather than experience).

I haven't tested this extensively (only a couple of prints on hardened gum
and hardened gelatin size) but given the fact that Cyanotype sensitizer is
problematic in being absorbed into paper fibers *even with
non-additionally sized paper*, I think the extra sizing would increase
image loss. In my attempts, sharpness (and contrast) was less with sized
paper too.

> ...
> Either way, if you're going to use the same negative, life is much easier
> if you shrink the paper first. And whether a hot pre-shrink will or won't
> hurt the cyano -- it's not necessary. My tests showed that a long soak at
> room temperature (from several hours to a day) shrank the paper as much as
> a very hot bath.
> (However, I only tested the couple of papers I was using at the time.
> Can't guarantee all are the same.)

Will give more importance to shrinking paper. But I'm a little skeptical,
have been seeing how dry gum *further* shrinks paper - as I said to Marek

> ...
> For just re-registering without any special contrivance, I find keeping
> humidity constant (if possible) is a big help, but registering from the
> center is even helpfuller -- so any miss-register is pushed to the edges
> where it doesn't register that much...

(As occured to me before while replying David) Probably this is the best
method to follow:
- Shrink well
- Expose both the cyanotype and gum layers at similar humidity/relaxation
levels. (I don't do so currently; I expose the cyanotype bone dry whereas
expose the gums with pretty humid/relaxed conditions...)