[alt-photo] Re: pigment problem

[Julian Smart]

Hi Katherine, thanks for the reply.

I had sort of come to the conclusion that it may be a sizing issue. Trouble 
is I have no  precedent for my problem in that I have only just started to 
use this paint and have just recently modified my sizing technique. I now 
size with a hardened gelatine, that is I add 2 drops of formaldehyde to a 
100ml of gelatine just prior to brush coating the size. I really wouldn't 
have thought that this would be a problem, or cause problems with different 
pigments, though I have noticed that the gelatine has hardened enough by the 
time I am sizing my fourth sheet to not allow a decently smooth coat.

Tomorrow I will try a different pigment, probably the Indanthrone you 
suggest and see how it goes.

Julian.





----- Original Message ----- 
From: "Katharine Thayer" <kthayer at pacifier.com>
To: "The alternative photographic processes mailing list" 
<alt-photo-process-list at lists.altphotolist.org>
Sent: Monday, February 07, 2011 11:08 PM
Subject: [alt-photo] Re: pigment problem


> Hi Julian, well, first a point of clarification about pigment names: 
> you're not printing with indigo pigment.  Indigo is PB 66, a pigment  so 
> fugitive that it is no longer used in any watercolor brands  (Winsor & 
> Newton was the last to discontinue it, about five years ago  or so, if I 
> remember right).  All paints named "indigo" nowadays  aren't actually 
> indigo but are convenience mixes of other pigments,  mixed in an effort to 
> replicate an indigo hue, and to follow  traditional naming convention, 
> they should all be named "indigo hue"  rather than "indigo,"  IMO.  But 
> never mind about that.
>
> While I often mix pigments myself for my own purposes, I try to avoid 
> convenience mixtures where I don't have any choice over what pigments  are 
> used.   I have found some pigment mixtures that produce a split  tone 
> effect in themselves (I'd have to go back to the archives to be  reminded 
> of what those were, since I've never gone on to use them in  my work) in 
> other words one of the pigments in the mix will be more  evident in the 
> lighter tones and the other pigment in the darker  tones.  If you're 
> interested in what those pigments were, I'm sure I  reported it to the 
> list when I made that observation, so it should be  in the archives 
> somewhere.
>
> What you've got here is phthalo mixed with quinacridone rose,  apparently 
> to shift the blue more to the red side, plus lamp black to  darken it. 
> If it were me and I were looking for an indigo-like hue,  I would use a 
> single pigment that is close to that hue rather than a  mixture. 
> Indanthrone, PB 60, is a very close approximation to indigo.
>
> All that said, I'm not entirely convinced from your description that  your 
> problem is related to pigment, however; it sounds to me more a  problem of 
> adhesion, or tooth, in other words that the layer isn't  attaching to the 
> paper as it should.  It would help to be able to see  exactly what you're 
> talking about, but if the layer is hardening  properly but then frilling 
> and lifting off, that's most likely to be  related to an inadequate 
> "purchase" of the gum layer on the paper.   So that's the line I would 
> pursue in trying to solve the problem,  look at issues of sizing, paper, 
> prior layers, to see if there's  something that is interfering with there 
> being enough tooth left  available to attach that third layer.
>
> Katharine
>