U of S | Mailing List Archive | alt-photo-process-l | Re: Paper negatives- Ink Selection&Baden-Baden

Re: Paper negatives- Ink Selection&Baden-Baden

Hi Henk,

Gorgeous oilprint. What is the difference, apart from weight of course, between 300 and 350 gsm paper? Is it the finish?


David H

On Oct 14 2008, henk thijs wrote:

I did a lot of paper- and Arista half tone negs; i used negatives for
cyanotype, gum and oilprinting and i was very often astonished about
two things:
the unpredictable (and often astonishing) results ;
the forgiving aspects of too long or too short exposure times doing
It was the list who first mentioned the dramatic effect on exposure
times due to humidity; so i have some experience and do not trust any
specific rules in order 'to make the perfect gumprint or equivalent';
i measure the amount of paint by eye, vary the exposure by looking a
bit after the humidity, downloaded some 3 dollar tutorials from Dans
Burkholder website for my printer settings and let it go.
Isn't that the way an apple pie is done after years of experience ?

Baden-Baden Horse racing Oilprint on 350 grs Fabriano nr 5 with
inkjet-plotter-foil negative (exactly same exposure compared to paper
neg ):


On 14 okt 2008, at 23:05, Katharine Thayer wrote:

> Loris, my question was a simple question: on what are you basing
> the statement that your exposure times are shorter than others'?
> because I'm not seeing other gum exposure times in the thread,
> never mind that even if there were, no valid conclusions could be
> drawn from the comparison. Instead of answering the question
> by pointing to posts I missed, or describing the data on which you
> base the assertion, you simply repeated it. It's not a helpful
> answer to the question, but I won't pursue it further; I'll take
> your word that there are these people you know about, somewhere,
> who print exactly as you print, with exactly the same emulsion,
> same paper, same light source, same negative media and exact same
> working procedures (same environmental conditions, we would also
> have to assume) who have to use longer exposure times because
> they're using negatives with more DR, or they're not calibrating,
> or their calibrations are flawed somehow. This is quite a
> remarkable finding, as I've never met two gum printers who use the
> same everything, unless they happen to be taking a workshop
> together and are using premixed emulsions and all other materials
> and equipment supplied by the teacher. Oh well, I don't really
> care, I was just curious. Back to check on my print,
> kt
> On Oct 14, 2008, at 11:08 AM, Loris Medici wrote:
>> Katharine, don't worry I'm pretty careful about this subject -
>> knowing (by
>> experience) you'll chime in every time it's brought up, to
>> clarify ;) I'm
>> getting older I guess; less and less surprises... ;)
>> I wasn't attributing the short exposure I'm using to curves at
>> all, that
>> was a side note (which should have been enclosed between parenthesis,
>> sorry). I was trying to say (indirectly) that since the DR (=density
>> range) and tonal progression of my paper negatives (made with the
>> HP 9180
>> all-inks grayscale setting, using the printer's plain paper
>> profile) are
>> close to ideal (in tricolor gum printing context - which is
>> supported by
>> the fact that the curve I devised for this particular combination
>> is the
>> smoothest and least dramatic one among all curves I did until now),
>> therefore, other people's longer exposure times could be caused by
>> the
>> fact that they're using negatives with more DR, which naturally will
>> require more exposure and a stronger / more dramatic curve to
>> counterbalance. Or they're not calibrating, or their calibrations are
>> flawed...
>> Hope it's clear, and makes more sense to you now. I perfectly
>> understand
>> the confusion I may have caused on your part.
>> Regards,
>> Loris.
>> P.S. BTW, I have compared my times with the times of people who use
>> similar light source, emulsion, negative media and working
>> procedures. I'm
>> perfectly aware of the parameters affecting exposure time and pay
>> attention to them.
>> 14 Ekim 2008, Salı, 7:18 pm tarihinde, Katharine Thayer yazmış:
>>> Loris, I'm wondering what data you're basing this last bit on, that
>>> other people's exposure times are longer than yours. It's
>>> generally
>>> not useful to try to compare exposure times because there are so
>>> many
>>> variables involved, but putting that aside for a moment, I've
>>> looked
>>> back through this thread, and the only reference to exposure times I
>>> can find is Guido's comparison between oiled and unoiled Epson PQ
>>> paper, 8 vs 48 minutes, with cyanotype. Since it was cyanotype,
>>> and
>>> since the paper is a heavier paper (27 pounds) than yours, it's not
>>> surprising that his exposure time for unoiled paper would be longer
>>> than yours, and we haven't even got to light source yet; to reach
>>> immediately to curves to account for a difference in exposure times
>>> seems rather a long stretch to me.
>>> Perhaps I've missed other posts that included exposure times for gum
>>> and paper negatives (my server doesn't accept some of the alt-photo
>>> mail, so I don't always see all the posts). At any rate, my times
>>> with oiled paper negatives run close to my times with inkjet
>>> transparencies, about 3 minutes, to add to your database on
>>> exposure
>>> times. I don't have any comparison with unoiled paper to offer,
>>> because that's not an option that makes any particular sense to me.
>>> But be that as it may, I can't see any reason why curves would
>>> account for a difference in exposure time. After all, the exposure
>>> time is determined before curves are even calculated, at least
>>> that's
>>> how it is with the system I use, and I assume it's the same with all
>>> systems; the curve doesn't change the exposure time. Besides,
>>> curves
>>> simply redistribute the tones within the print tonal range that
>>> particular emulsion can print under that particular protocol; they
>>> don't extend it, so there's no logical reason curves would have any
>>> effect on exposure time.
>>> Katharine
>>> On Oct 12, 2008, at 11:23 AM, Loris Medici wrote:
>>>> I use the grayscale using all inks (not black and gray - if present
>>>> - inks
>>>> only), plus, I choose plain paper as the media. Fortunately, with
>>>> my inks
>>>> the printer lays just enough ink giving an almost perfect
>>>> negative in
>>>> terms of density range (something around log 1.0), and the curve I
>>>> use for
>>>> gum prints are is the least drastic and most smooth one among my
>>>> curves
>>>> collection for many processes and paper. In fact, I think that's
>>>> why other
>>>> people's exposure times are considerably longer compared to
>>>> mines...
>>>> (!?