Re: oil printing
Sorry, I forgot to answer the other part of your question, why in oil
printing a negative is used, and in gumoil, a positive, when it seems
like they should work sort of the same way. You're right that in
both cases the oil paint is deposited mainly in the shadows and less
in the midtones and highlights, so it seems like you'd need the same
kind of intervening matrix. The difference is in the qualities of
gelatin vs the qualities of gum, which makes them behave differently
when acting as a resist for the oil paint. For gumoil, you use a
positive to expose the gum backwards (more hardened gum in the
highlights, not much or no hardened gum in the shadows) and then you
wash off the unexposed gum, leaving the hardened gum to serve as a
resist in the highlights and partially in the midtones and the paper
free to accept the oil paint in the shadows. For oil printing, you
expose a negative to harden the gelatin most in the shadows; when you
put it in water to wash out the dichromate and to swell the gelatin
in the highlight areas. Then the oil paint is applied; it sticks to
the hardened gelatin in the shadows and is repelled from the swollen
gelatin in the highlights. Same result, but opposite ways of getting
there. Does that make sense?
Hope that's helpful, and Henk, I hope you'll set me straight if I've
got this wrong somehow. I've done one gumoil in my life, just to see
what it was like, and no oil prints, but this is how I understand the
principles involved, and since no one else seemed to be answering the
question, thought I'd just blunder in.
On Sep 26, 2008, at 7:21 PM, Katharine Thayer wrote:
Sorry to barge in here, but I'm having trouble following this
conversation. Dirk asked a question about why there's no hardener
in the gelatin layer, and since the subject line is "oil printing"
I assumed he was asking about the gelatin layer in oil printing.
But the answer that came back seemed to be about the gelatin layer
that acts as a size for gum printing, which I, for one, found quite
On the chance that I had it right in the first place and the
question was about oil printing, the answer is that there's no
hardener in the gelatin because in oil printing you don't want the
gelatin to be hardened as a whole layer, as you would if you were
using the gelatin as a size for gum printing. You only want the
gelatin hardened where it's exposed; that's the purpose of the
dichromate. Just like you wouldn't put a hardener in the gum
that you're using for a gum print, because you don't want *all* of
the gum hardened, just the gum that's exposed. Hope that's the
question you were wondering about..
If I was wrong and the question really was about sizing for gum
printing, then I might suggest that it can be helpful to change the
subject line if the subject changes, so people trying to follow the
thread can make sense of it. Thanks,
Oh, and by the way, while we're confusing the two issues: part of
the answer about sizing for gum printing seemed to suggest that if
the glyoxal were mixed into the gelatin before being applied,
rinsing might not remedy the yellowing problem. In my experience,
that's not a worry. I apply the gelatin with the glyoxal mixed in,
and rinsing does remove the yellow, in fact I don't bother to rinse
separately after sizing, because though the sized paper does turn
yellow in a few days, it returns to pure sparkling white in the
development phase of gum printing. So I don't find any need for a
separate rinse. There, now I've given you an answer for either
possible meaning of your question. :--)
By the way, I enjoyed seeing your prints, and noticed that you took
a workshop from Kees. Look forward to seeing your progress,
On Sep 24, 2008, at 11:52 PM, Dirk-Jan Treffers wrote:
Just a wondering thought: Is it on purpose that you omit the use
of hardener in your gelatine layer? I also found more or less the
same recipe on alternativephotogrphy.com, and there also the use
of a hardening agent like glyoxal wasn't mentioned.
Is that correct, and if so, what's the reason for that?
And another question (you see, I'm curious)... why is that in
oilprinting, a negative is used, while in the gumoil process
(which sounds more or less the same...) you need a positive....
2008/9/25 Judy Seigel <email@example.com>
On Wed, 24 Sep 2008, henk thijs wrote:
OILPRINTING is a contact-procedee like gum, cyano etc..
Coating a 300grams paper -like you use for gum- with a 10%
gelatine, three times, let dry and coat with a 6% potassium
Like gum, put the neg on top , UV-light for twice the time you
Wash out the chromate, gelatine is partly harded and now you have
your matrix for oiling.
Info about the ins and outs are difficult to find; in David's
book, the chapter about oilprinting is a bit thin. I had to do a
lot of testing (or better: paperbasket filling with rubbish)
before making oilprints ; but if you succeed there is no need for
a darkroom anymore (and if you have anyway a suitable negative and
some chromate ....).
The books and magazines of Demachy's period when oil printing hove
into view have many articles about that process, some, I daresay
I found them appealing, but resisted for a number of reasons,
including and especially because I'm allergic to the solvents (and
warn anyone using oil paints be careful: Turpentine is one of the
two most allergenic substances for humans. The other is chrome,
tho I don't know if that extends to all forms, including
dichromates, or just shiny bumpers.)
In any event don't get your hands in the turp, or yr feet either
for that matter... I now use odorless mineral spirits when the
need arises -- tho some labelled "odorless" lie -- so far OK, but
I'm careful, ie, don't leave the stuff in an open container, and
if I have it on rags or whatever, dispose of them in a closed
container in another room... etc.) The worst, probably, is in a
classroom -- imagine 30 palettes or trays in an enclosed space wet
with turpentine !!!! (Yeah, in the good old days.)
Meanwhile, I'll check some of those period annuals, or whatever I
find in the Mississippi delta AKA my book shelves. Or aren't there
indexes of that literature somewhere?
PS to Henk: Sorry I can't join in the chorus of praise, because I
have to switch partitions before I can see those prints... gotta
get myself into giraffe, or whatever it is...
But soon, I hope....