U of S | Mailing List Archive | alt-photo-process-l | Re: cyano on gessoed Al

Re: cyano on gessoed Al


Is 5% the final concentration of AD in the emulsion you coat?

In my experience, for the agar layer to be uniformly spread, I needed
to provide tooth to the acrylic gesso ground. For this, I added the
supernatant from a 10% suspension of finely sieved granite powder
(aluminum oxide - Al2O3) before spreading it 4x or more in directions
perpendicular to the previous one and drying each application (as you
suggested). After drying for at least 24 hours, this ground was
lightly roughed up with a fine sand paper (circular motion). The agar
layer was applied to the ground as follows:

The agar (0.5%) plus Al2O3 (as in the ground) was melted in boiling
water before applying it to the gessoed sheet. It was air-dried for
at least 24 hours. I did not add gelatin to the agar. A cyano pass
followed (1A + 2B + 3 drops of gum arabic + 3 drops of 40% citric
acid), exposed for 30 min, and developed in diluted vinegar (1
vinegar + 5 water). The shadows printed well, the low mid-tones were
visible, but the highlights washed out.

I will follow with gelatin size (HCHO hardened) containing Al2O3 and
do gum passes to see what happens. Will let you know what happens.


On 14-Apr-09, at 6:46 AM, Loris Medici wrote:

Hi Rajul, I missed this one below, sorry.

I use my standard 5% AD concentration for every kind of surface. I
the Al sheets for the same time as paper.

I just purchased agar-agar and will try it on painted aluminum panels
soon. The panels are said to be painted with electrostatic powder
which is melted and cured in special owens. I hope agar-agar will
be able
to adhere.

Do you size the agar agar layer with gelatin (or include some
gelatin in
the agar agar coating)? This is in my things to try list...


11 Nisan 2009, Cumartesi, 9:28 am tarihinde, Rajul yazmış:
Hi Loris,

When you do gum on prepared Al sheets, what concentration of AD do
you use, and how long do you need to expose relative to paper

Looks like I will have to continue building tooth at every step if I
want the colors to blend between successive passes.

Thanks for your input. Rajul

On 10-Apr-09, at 11:52 AM, Loris Medici wrote:

Rajul, thanks for the update. I'm very interested in the agar-agar
-> seems to be useful for other things too (sizing paper - from
Novo - and non-toxic carbon - from Halvor Bjoengaard)...

I currently wait for Henk coming back from his trip -> will continue
trying with "beer coating" after hearing back from him.


9 Nisan 2009, PerÅ�embe, 10:53 pm tarihinde, Rajul yazmÄ
To all Al friends,

This is a preliminary observation but I have been able to do
cyano on
gessoed Al sheets.

I added finely sieved Aluminum oxide (Al2O3) to the diluted gesso,
and applied multiple coats of it
to achieve the desired opacity. Al2O3 killed the super white of the
gesso, provided tooth, and did not increase the pH. After drying
lightly sanding coated sheets, I applied 1% agar, and dried them
overnight. I still have to improve on the smoothness of the agar
and will try 0.5%. As expected, agar provided the porosity that
cyano printing.

A cyano mix of 1A + 2B required a 30 min exposure and printed all
details. However, on development in diluted vinegar, only the
and low mid-tones stayed; all highlights washed out.

I will size these plates and see what gum passes will do.

Details of the process will follow once I am able to confirm my