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

Re: cyano on gessoed Al

Hi Rajul,

I didn't understand what exactly you're referring to by final
concentration. See below:

- coating solution: 1+1 pigmented gum + dichromate
- gum solution: 1+2 gum powder + water

BTW; see Halvor's Chiba System for a nice method for applying agar agar
onto plates:

(page 22, 4.1. Recipe -> Covering layer)
(page 34, 7. Summary of Work Steps)

I coated a bare aluminum sheet last night (no glycerin and gelatin in the
solution, just 1% agar-agar), since there wasn't any frame material around
I just poured the hot solution on the sheet and spread it with fingers
(it's hot!!! will use a comb next time hehehe) - just like carbon printers
do when pouring carbon tissue. This morning it was party dry (due uneven
coating), but the dry parts were very tough and firmly attached to the
sheet. It's a nice surface, very smooth (looks being
so, agar agar is actually pretty porous in micro scale), very transparent
and shiny. Will try to print on it tonight. If that works then I wouldn't
need gesso at all! I will just apply this coating over white painted
aluminum (or bare aluminum if I need that peculiar look -> metal
background instead of white)!

Will return back with the result (if I manage to get any!)...


14 Nisan 2009, Salı, 6:52 pm tarihinde, Rajul yazmış:
> Loris,
> 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.
> Rajul
> 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
>> expose
>> 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
>> paint
>> 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...
>> Regards,
>> Loris.
>> 11 Nisan 2009, Cumartesi, 9:28 am tarihinde, Rajul yazmı�:
>>> 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
>>> exposures?
>>> 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
>>>> stuff
>>>> -> seems to be useful for other things too (sizing paper - from
>>>> Alberto
>>>> 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.
>>>> Regards,
>>>> Loris.
>>>> 9 Nisan 2009, Per��embe, 10:53 pm tarihinde, Rajul
>>>> ±��:
>>>>> 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
>>>>> and
>>>>> lightly sanding coated sheets, I applied 1% agar, and dried them
>>>>> overnight. I still have to improve on the smoothness of the agar
>>>>> coat
>>>>> and will try 0.5%. As expected, agar provided the porosity that
>>>>> aids
>>>>> 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
>>>>> shadows
>>>>> 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
>>>>> observations.
>>>>> Rajul