[alt-photo] Re: Multi coat Gum -3rd+ coats tends to wash off

[Loris Medici]

I'm not sure if changing the order of layers does indeed help the emulsion
to cling onto paper. (I don't think so but that's gum!)  My understanding of
Keith's (highly plausible) practice comes from the fact that printing cyan
first makes easy to register subsequent layers. Also what really ruins a gum
print is often an error in the cyan layer (paraphrasing Keith - I agree
completely), so printing it first will let you decide if it's worth to
continue and/or allow to change your strategy before it's too late. (Again,
highly plausible explanation; even if you don't follow their path exactly,
it's very beneficial to listen to the masters...) The only disadvantage (if
you like...) of this method is that you have to choose pretty transparent
yellows and reds/magentas for subsequent layers - if not, you'll have a
distinct haze over your dark tones. OTOH, that could change the look
completely. May work for you or may not...

If your emulsion doesn't leave the paper in bits and pieces (flaking that
is), then you probably don't have to fiddle with pigment amounts.
(Especially if you're happy with the colors you're getting.)

IME, if you use a relatively thick coating solution, you definitely need to
brush pretty harshly to be able to get a nice smooth and thin layer. Maybe
you should try to lightly size the paper (with 3% hardened gelatin or
diluted PVA size) to minimize the risk of staining.

Play with the exposures a little bit - just as Paul mentioned. That could
help indeed, in case it doesn't negatively affect your darks in the same
time.

What exactly is your coating solution's formulation? If it's gum/pigment +
dichromate 1:1, you may try to add extra 1/2 to 1 part water and see how
that works. (1 gum/pigment + 1 dichromate + 1/2 or 1 water...)

Hope this helps & good luck!
Regards,
Loris.


-----Original Message-----
From: alt-photo-process-list-bounces at lists.altphotolist.org On Behalf Of
pfriedrichsen at sympatico.ca
Sent: Friday, February 26, 2010 1:16 AM
To: The alternative photographic processes mailing list
Subject: [alt-photo] Re: Multi coat Gum -3rd+ coats tends to wash off

John,

I reversed the layers by moving the cyan to the first layer rather than the
last. Funny that this allowed the top layer (now magenta) to adhere well.
There was a post that I found in the list archives of Sept 2008 by Keith
Gerling who suggested printing cyan first.

Now having said all of this, I still do believe that it shouldn't matter
which color goes first in terms of adhesion so I suspect that the amount of
dried gum left after development  must be in excess. I will do some
adjustments by diluting the gum concentration, and if need be, the pigment
load as well. Your suggestion of going over it with a dry foam roller may
also be worth a try however I do find that the slightest pressure on the
paper from a foam roller increases staining, a tleast that was my experience
when I gave it a go some time ago.

Peter Friedrichsen

At 05:39 AM 02/24/2010, you wrote:
>Hi Peter,
>
>Yes, there are some that don't size but you may get staining issues. 
>Also, when stretching and developing you may lose some of the manufacturers
size.
>It is gum compatible because it has a good wet strength and is 
>dimensionally stable.
>
>I use FAEW HP, sized with gelatine and have put down 7 or 8 layers on 
>one image. I'm with Loris here on the thickness of your layers. I find 
>I can get a very thin layer by coating with a foam brush and then using 
>a dry foam roller to even out the coating.