[alt-photo] Re: pigment problem

[Katharine Thayer]

Ah, then I'm sure of it.  If the gelatin is setting up while you're  
brushing it on, it's almost certainly making too thick a gelatin  
layer, which may fill up the tooth to the extent that there wouldn't  
be room for three gum layers to hang onto the paper fiber.  You need  
to keep the gelatin warm throughout the sizing process so that it  
will soak deeply into the paper rather than sitting on the surface.    
I keep an extra microwave oven in my sizing area and reheat the  
gelatin (very gently on low power) occasionally to keep it above 120  
F but under 140 F.   Others keep it warm in a vacuum jug or with a  
water bath; whatever it takes.  I would almost bet money that that  
should fix the problem for you.


On Feb 7, 2011, at 4:10 PM, Julian Smart wrote:

> 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
>>
>>
>
> _______________________________________________
> Alt-photo-process-list | http://altphotolist.org/listinfo
>
>