U of S | Mailing List Archive | alt-photo-process-l | Re: gum prints on Yupo

Re: gum prints on Yupo

Silica fume looks good.  Thanks for the tip. I'll try that when I run
our of pumice.

I found two large jars of animal glue dry gesso mix on the sale table
of a craft store , and bought both of them for $10

Bad.  On first attempt, the gesso slid right off the surface as soon
as I brushed on gum emulsion. Added gluteraldahyde and it stuck to
plywood (still won't stick to aluminum), but it stains horribly.

2008/11/4 Loris Medici <mail@loris.medici.name>:
> Hi Keith,
> I have two different kinds of gesso. Both Daler Rowney brand, one System-3
> white, the other is Cyrla black. System-3 white works well in terms of
> keeping the gum image (but still exhibit a chemical - not pigment! -
> general stain). Cyrla black reacts just as you describe and doesn't hold
> the gum image (even with added calcium carbonate) at all; as soon as you
> put the image in the development water, it leaves the substrate instantly
> (exactly as you experienced / showed in your first trial with Artboards
> gesso).
> I plan to change the gesso additive from calcium carbonate to silica fume
> -> hoping it won't react with dichromate but still provide tooth for gum
> emulsion... Better, I will look for proper flexible plaster -> for making
> "gum-o-fresco"s ;)
> Your gesso tests are beatiful / interesting! I liked most the last one...
> Regards,
> Loris.
> 3 Kasım 2008, Pazartesi, 7:26 pm tarihinde, Keith Gerling yazmış:
>> Loris,
>> I have experienced a definite pigment stain with that kind of size -
>> an odd "solarized" look where the highlights stained and the midtones
>> would clear.  A coat of hardened gelatin seemed to help.  I wonder if
>> you observe the same effect as I do using a similar mix:  when I brush
>> on the emulsion, I detect a very obvious separation where the surface
>> draws the dichromate away from the pigment.  Initial brushstrokes are
>> very clearly orange and only with repeated brushing does the emulsion
>> seem to "come together".  In my case the exposures are much longer,
>> but that may be due to the fact that I am using lampblack and it is
>> self masking.  In any event, my normal exposure with 1 part gum to 1
>> part saturated pot di is 8 minutes, and I'm having to use 20.
>> Keith
>> 2008/11/3 Loris Medici <mail@loris.medici.name>:
>>> I had encouraging results printing on yupo coated with acrylic gesso +
>>> calcium carbonate mixture. I just did two tests, one 8 minutes, the
>>> other
>>> 4 minutes exposure. Both were highly overexposed (even a foam brush
>>> wont
>>> clear darkest part of the image). Will try 02:00, 01:00 and 0:30
>>> exposures
>>> and then share the results... Coating is easy as long as you brush
>>> presistently for a long time (emulsion doesn't bead much) and you keep
>>> the
>>> emulsion very thin (if not, flaking occurs).
>>> One important problem is: the base gets stained (not pigment, some kind
>>> of
>>> chemical stain), and doesn't seem to clear with sodium metabisulfite.
>>> Will
>>> see how it goes with shorter exposures. If it continues to stay so then
>>> I
>>> won't be able to get pure white -> only ecru / warm background. Not a
>>> problem for some images, big one for others...
>>> The base coating consists of:
>>> 1 part acrylic gesso
>>> 1 part calcium carbonate powder
>>> 1/2 part water (all by weight)
>>> mixed homogenously giving a creamy consistency. Applied with a foam
>>> brush,
>>> smoothed gently with a watercolor wash brush.
>>> I must admit it's not much interesting for Yupo. But if I manage to
>>> make
>>> it work, it can be used as a nice way to print on rigid / impermeable
>>> and
>>> smooth substrates such as aluminum sheets or MDF, HDF or plywood...
>>> More later,
>>> Loris.
>>> 2 Kasım 2008, Pazar, 5:43 pm tarihinde, Marek Matusz yazmış:
>>>> Erie,
>>>> If you look closely at the pictures that I posted you can see the
>>>> "imperfections" in the print, but these are best prints on Yupo that I
>>>> kept.  Gelatin sizing was a total disaster with the gum layer not
>>>> sticking
>>>> to it at all.
>>>> What worked best for me is no treatment to the sufrace at all. Very
>>>> thin
>>>> gum layer (means dilute gum solution) rolled with a gum roller gives
>>>> decent results. It seems that the thinner the gum the better the
>>>> results.
>>>> My exposures got very short as well, around 30 seconds. I wonder if
>>>> scrubbing the paper with cleaning powder would help a bit?