Re: Your print on Al

[Loris Medici <mail@loris.medici.name>]

Dear Rajul, I will cc this to the list also (it may be useful for others
too)...

Negatives:

I use a thin paper for the negatives; it's Keith's infamous "18lb
Translucent Inkjet Bond" from Freedompaper. I print my negatives with a
HP9180 printer, using "Gray Only" inks. I use a simple curve (actually no
curve, just levels adjustment, which is applied to the positive, not to
the negative), which was derived by printing a 101 step tablet at standart
exposure time (which was determined not by testing, but by feel!) and
adjusting the gamma slider so that the reading from the printed 18% gray
patch matches the reading from the original file at the same location.
Actually, not much critical with gum; as you have so much play in coating
solution formulation, exposure, development, and whatnot...

Most info below comes from my exchanges with Keith:

To prepare the sheet I first mix 25g acrylic gesso + 50ml water + 50g
calcium carbonate powder thorougly (you may also replace 10g calcium
carbonate with 10g titanium white to get a whiter base and slightly less
absorbent ground), then I add further 50ml water (stir/mix thoroughly
again) to dilute the mixture for easy application. I apply the mixture to
the cleaned / degreased (with rubbing alcohol) sheet using a 5" foam paint
roller. I quickly dry the first layer with a hairdryer at hottest setting
and apply a second layer (using the roller at a perpendicular angle to the
previous layer). I repeat this until I have 4 layers (always altering
directions). The criteria/purpose is to have an even and opaque layer. I
leave the sheet to dry thoroughly for a day or two, then I prepare a 1.5%
gelatin solution (w/ 0.5ml formalin) and apply this to the sheet. It's
ready to print on after the gelatin dries and hardens. You may opt to sand
the surface for a smooth finish, since the texture is quite pronounced
when coating with a foam roller.

Side info:

I use 5% ammonium dichromate as sensitizer. My coating solutions consist
of 1:1 gum/pigment:dichromate. I expose the sheet for 12 minutes (base
exposure; may differ dependint to pigment/sensitizer strenghts and intent.
I use 40W 24" UVBL tubes BTW...) and develop face up for 30 - 40 minutes.
Agitating the tray and changing water every 10 minutes.

For obtaining the sheets:

I obtain my sheets from specialized wholesale stores. I use 0.3mm (28
gauge / 12mil) thick sheets which come at 1x2m (39 3/8x59") size. I have
them cutted to size for few extra bucks at a near workshop. The whole
sheet + cutting will cost about $15. That is $1 per 13x15 6/8" sheet (for
instance); comparable to fine watercolor paper, with the added bonus of
being an ultra-quick drying material/surface which is also very durable
(much more than paper) and recycleable - just coat another ground layer
over a bad print or use the back side since it's exactly the same, unlike
most papers... I can't speak for / suggest anything for your case, since
we're in very different environments (Turkey <--> US?)...

Hope this helps,
Loris.


2 Mart 2009, Pazartesi, 1:15 am tarihinde, Rajul yazmış:
> Hi Loris!
>
> I am writing to you after a long time! I must tell you how far I feel
> this medium will take you and your negatives in the
> days to come. You have probably hit a mine.
>
> I would very much like to know how you produce your large paper
> negs.  I also would like to have a go at printing on Al sheets and
> would appreciate details of the type of media you work on (where you
> obtain it)  and how you prepare the surface.
>
> I have very much enjoyed working on Masa and it was worth all the
> trouble taming it. Once mounted on to a support, it takes pretty
> harsh treatment and at least 4-6 passes!
>
> Many thanks for any info you can provide on Al.
>
> Rajul