On Thu, 19 Jan 2006, Gordon J. Holtslander wrote:
> Liquitex make a clear acrylic gesso - I assume (bad practive) that is has
> no titanium whitener.
Definitions change over time -- I remember when a "dork" was a jerk,
which is to say a nudnik, and now it seems it's an expert, geek or techie.
So I say with some reservations that by definition *traditionally* a gesso
had to have a whiting substance in it. To quote Mayer: It's made by mixing
"an inert white pigment such as chalk, whiting or slaked plaster of Paris
with an aqueous binder such as a solution of glue, gelatin or casein."
I don't think by the way that gesso has titanium -- Mayer has a section on
"Defects of Gesso panels" which I haven't read for 105 years, but my
recollection is that they would be some kind of cracking, which presumably
(better word than "assume," n'est-ce pas?) would be obviated by the
gelatin.
When I learned to make gesso, 103 years ago, we slaked plaster of Paris...
and somewhere along the line I was told that *rotten* plaster made the
best gesso, that is, you slake then keep a year or so til it rots. I made
some up and worked off it for a long time -- I haven't used the gelatin
gesso mix for a while (Bernie Boudreau's version is cited in P-F #6),
because for my printing, plain Knox hardened in glyoxal or formaldehyde
proved easiest & best. But I still have a couple of inches of the rotten
plaster in a gallon container.
That's the beauty of rotten plaster -- it keeps !
PS. Gord: Does Liquitex call that clear stuff "gesso", or ...? Is "white
blue" a misprint for "white glue"... or... ? (Elmers, maybe?) How do you
clean the foam roller? Any special kind of foam?
TIA,
Judy
>
> I have been playing around with sizing techniques.
>
> Did a mix of gelatin (250 ml) and a little (20 ml) white blue, hardened
> with chrome alum, rolled on with a foam roller. Seemed to give a much
> smoother/cleaner surface than plain gelatin. But then the gelation coat
> may simply have been poorly coated.
>
> Gord
>
> On Thu, 19 Jan 2006, Ryuji Suzuki wrote:
>
>
>> I've tried gesso mix but one objection I had was that the acrylic
>> gesso is gritty because of matting agents in the mix. Another
>> objection I found is that the gesso contained titanium white and other
>> things I would not want to have in my prints unless archivality is
>> proven in the particular combination. Titanium white is very
>> photoactive and generates a lot of radical chain reaction in the
>> material when exposed to UV, and this was the main cause of problems
>> in early days of RC papers. Photographic industry learned enough and
>> today's products have good amount of means to prevent the problem, but
>> I am not sure of gesso in sizing layer.
>>
>
> ---------------------------------------------------------
> Gordon J. Holtslander Dept. of Biology
> holtsg@duke.usask.ca 112 Science Place
> http://duke.usask.ca/~holtsg University of Saskatchewan
> Tel (306) 966-4433 Saskatoon, Saskatchewan
> Fax (306) 966-4461 Canada S7N 5E2
> ---------------------------------------------------------
>
>
Received on Thu Jan 19 21:24:16 2006
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