U of S | Mailing List Archive | alt-photo-process-l | Re: Printing on Al - my experience

Re: Printing on Al - my experience

Hi Rajul,

Thanks for the info.

My question about the gum ground preparation:
    30 ml of 14 Baume Gum Arabic

Do you buy gum in a liquid or powder form?
If in a powder form, how do you mix it?
If a liquid from what supplier do you get it from?


Quoting Rajul <eyeear@shaw.ca>:


I tried many combos of acrylic gesso plus additives (CaCO3, granite
dust, then sand flour) and realized that to keep any of these in
suspension, the viscosity of the mix had to be increased. This was done
by adding gum arabic as detailed in the recipe I communicated earlier.
The gesso alone does not provide enough tooth for repeat gum passes.

Could you please re-word the question you have re. the consistency of
the gum:water mix?


On 9-Jul-09, at 10:04 PM, Jacek Gonsalves wrote:

Hi Rajul,

Thanks very much for all the information!
Though wouldn't just the ground of Acylic gesso give you the tooth it would need to apply coats of whatever alternative process your using?

Btw what is your consistency,/mixture of your 30ml Gum Arabic to water?


Quoting Rajul <eyeear@shaw.ca>:

I was able to get good prints on Al by the method I describe below.
Although I continue to fine-tune the procedure, the set of prints I
have are happy outcomes - flaws and all. I am thankful that gum arabic
served to increase the viscosity sufficiently to keep the sand flour
particles in suspension through the coating steps.

Clean plates w soapy water (tear drop test for cleanliness).
Clean 3x w 99% isopropyl alcohol.
Mask borders if desired w painters' tape or tackier tape.

30 ml of 14 Baume Gum Arabic
60 ml water
Add acrylic gesso (I used Stevenson's) to desired opacity
10 g Sieved Sand Flour
Pot. Dichromate powder equivalent to the concentration used to get
shadows to print
(I found 2% more than enough)

a. Use a dampened, squeezed out roller
b. Pour an aliquot of the stirred ground on to plate and apply it
uniformly w roller
IMPT: helps to have roller barely charged. Hold it in a
sandwich bag while c and
d (below) are carried out to prevent it from drying
c. dry coat w hair dryer set on hot
d. UV for 1 min to harden entire coat
e. Turn plate 90 degrees and repeat b-d till ground is of desired

4% gelatin hardened w HCHO and containing ever clear is applied on
3 consecutive days (allowing gelatin to dry for 24 hours between
each application).

- Use a 10% amm. dichromate stock for mixing w gum and water color pigment
- It HELPS to dampen plate w a wetted, hand-wrung towel before brushing on
emulsion with a dampened, flicked, foam brush to get streak-free spreads.
- dry coat w an overhead fan.

- If, during development of an exposed gum layer bubbles form between the
ground and the Al surface, REJECT the print: the dried bubbles prevent
close contact between the negative and the printing surface during subsequent
gum passes. Rate of bubble formation was 1 in 24 plates in my hands.

Can be done on top of gum. This requires long exposures (~1 hour in the
shade on a sunny summer day).

- If there was any balling of the gelatin when the gum emulsion was applied
(resulting in raised dots that may be colored or white), the cyano
emulsion will clear them. In some prints, I found these dots to be
a windfall!

I hope the above persuades more gummists to take on Al. Questions or
comments are welcome.