U of S | Mailing List Archive | alt-photo-process-l | Re: agar sizing

Re: agar sizing

agar is not used for growing bacteria but to prevent them to spread, so that they grow in colonies which can be seen at naked eye. You can preserve it as usual (thymol, sodium azide, etc.). The chemical difference between agar and gelatin is that the former is a polysaccharide (like cellulose), the latter a protein.
yes, I know that the jelling properties of agar are stronger than gelatin. But as you want to close the pores of the paper, you need a little more substance on it.

Hi Alberto (and Damiano), very interesting indeed. What about preserving
the layer? Isn't agar-agar used to grow bacteria in glass dishes? (In
laboratories.) Is it durable as hardened gelatin? (Probably gelatin also
is vulnerable in humid conditions???) If it's durable then I would prefer
it to gelatin because it leaves formalin and such out of the procedure. I
can't say I like formalin much!
Damiano, I don't think you need "proper jelly" in the paper -> something
which makes the fibers less absorbent / less vulnerable to disintegration
would be fine.

16 Mart 2009, Pazartesi, 4:20 pm tarihinde, Damiano Bianca yazmış:
ciao Alberto.
molto interesante. Un pasticciere mi dice che il potere gelificante
al 2 x mille. Non sei forse troppo alto?
very interesting but a pastry chef tells me that the gelling power starts
about 2 gr/liter.

2009/3/16 Alberto Novo <alt.list@albertonovo.it>
I have given a try to cuprotype on BFK sized with 1.7% agar-agar by
(2% was setting too fast). There is no need to harden the size, because
is soluble only in boiling water, and thus I used my paper in a few
As the results were satisfatory and agar sizing looks promising, I
wonder if
you have any experience with this size and different processes.

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