Re: gum prints on gessoed aluminum

[Keith Gerling <keith.gerling@gmail.com>]

I made these prints today.

http://www.gumphoto.com/gessotest4.jpg
http://www.gumphoto.com/gessotest5.jpg

1) 1 coat plain Art Boards gesso
2) 1 coat 1 to 1 Art Boards gesso and ground pumice (thinned with water)
3) sized with glut-hardened gelatin
4) two coats of gum (I'm shooting for 1 coat, but I'm way out of practice)

the graininess is in the negative - shot at very high ISO and the
negative is un-oiled paper

2008/11/3 Keith Gerling <keith.gerling@gmail.com>:
> 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?
>>
>>
>