arkins@banet.net
Thu, 25 Mar 1999 23:33:49 -0500
Dave:
I have been doing oil printing, and using Pollmeier's formula, which is
excellent. I add the starch (I use potato, but corn will do as well)n
uncooked, by mixing it with a little water and adding it to the hot gelatin at
the same time as I'm adding the alum/acetic acid solution. The hardener
really helps to avoid blistering and having the gelatin detach from the paper
base. Remember that the inking process involves a lot of abrasion of the
gelatin by the brush, so a little hardening makes the gelatin sufficiently
tough to resist tearing when being pounded by a bromoil brush. The starch is
essential because it adds "tooth" to the gelatine surface which allows the ink
to adhere better. (In my opinion, it is an essential additive. . .)
With regard to coating, soak the paper in hot water first and squeegee on to
plexi and surface dry with a paper towel. Use a narrow-spouted pouring
implement (I use an olive oil dispenser) with a long spout, which will allow
you to pour the hot gelatin really near the paper surface. (This avoids air
bubbles, a real problem with coating gelatine emulsions.) "Tease" the
gelatine across the paper surface with a rubber hair comb, working quickly
before the gelatine sets. After about 10 minutes, remove the coated paper from
the plexi and hang up to dry, using clips on each corner to minimize curling
as the coated paper dries.
Another anti-bubble aid is to strain the gelatin through a woman's nylon
stocking as you pour it from the container on to the paper. Also, using
boiled (and subsequently cooled) water eliminates dissolved oxygen from the
water used to prepare the gelatin emulsion, which is another desirable
techinique to employ.
Oil printing is fabulous, if frustrating at times. When you do your
pre-inking soak, try 1/2 hour at 68 deg. Fahrenheit. Temperatures much higher
than 75 deg. F. are conducive to blistering.
keep me advised on your progress!
Regards
Joe Arkins
NY, NY
FotoDave@aol.com wrote:
> Hi, I am searching through my old files and found this formula (from Klaus
> Pollmeier) for oil printing:
>
> - Prepare 140 ml of a 15% gelatin (Bloom Index >200) solution
> - add 14 ml of a 15% potato starch (dextrine) solution
> - while stirring, slowly add 14 ml of a hardener, made by mixing 6 ml
> of a 6% sol. of acetic acid and 8 ml of a 1% sol. of chrome alum.
>
> I would like to try oil printing but have some questions:
>
> Will food gelatin work? How much should I use?
>
> Can corn starch be substituted in the above formula? Also, I assume it is
> uncooked starch (rather than cooking into paste). Is this true?
>
> Why does the gelatin need to be hardened? How can hardened gelatin work?
>
> Thanks in advance for any suggestion / comment.
>
> Dave S
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