Re: Paper negatives- Ink Selection

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

Katharine,

AFAIK, Keith uses same gum (which he purchased in Istanbul from my
supplier), same stock gum strength, same negative media (18lbs translucent
inkjet bond), same paper (Masa), similar light source (UVBL), slightly
stronger dichromate concentration (saturated PD whereas I use 10% AD) but
his exposure times are about 1.3 stop slower than mines (his 15 minutes
versus my 6:30 - oiled or non oiled negatives I don't remember), which I
find remarkable.

Guido's cyanotype exposures with oiled Epson PQP are 8 minutes, whereas my
exposure times are 9 - 12 with "Pictorico" which should be way faster than
oiled Epson PQP (see Guido's Arista exposure times for instance). We use
similar light source (UVBL), even exactly the same lightbulbs (Philips
TL'K40W). And I find this remarkable too. (I print Cyanotype using
colorized negatives BTW, not grayscale.)

Those were the facts / starting points that made me curious / think about
and realize / assert what you seem to object.

Most importantly, I know a guy named Loris, who's printing using the same
parameters (printer, media, paper, emulsion, working conditions and work
flow ect. ect. - you name it) except for the fact that he uses colorized
negatives made on Pictorico using premium glossy photo paper profile,
calibrated for cyanotype - which prints very well with gum with much
better shadow separation (blacks are comparable), but then his exposure
times are considerably longer than mines (who's printing all-inks
grayscale negatives on translucent inkjet bond).

You somehow doesn't like exposure times comparisons, but if we didn't
share & compare exposure times (considering working conditions /
procedures) and be curious about them, I wouldn't realize this (which
actually should be obvious since I actually tested it, not knowingly).

Now all this was because I said "HP9180 all-inks grayscale negatives are
perfect for tricolor gum" (to remind the main topic / the actual assertion
I've made), which is definitely useful information for those who have that
printer (which is very nice also for making stable, high quality color or
monochrome inkjet prints), unobjectionable to me until someone else proves
it wrong and/or comes with a better way (read as: less exposure time and -
not necessary - richer tonality) to do it.

So, if someone uses that information to get better results than what they
were getting before, then this is good info for them. If I'm proven wrong,
then that's good info to me since I'll learn an even better way to do it
(by asking them / questioning causes). A good example to win-win
situtations...

Hope that's even clearer for you,
Loris.

P.S. Again, if we weren't talking about exposure times -> we wouldn't
arrive to that conclusion (even if you don't buy it). Most importantly, we
wouldn't talk & think about reasons because we would dismiss / ignore the
exposure times stated by others -> "knowing it's nonsense to compare"...
That's my second point. (To remind again, first point is: HP9180 all-inks
grayscale negatives are perfect for tricolor gum...)


15 Ekim 2008, Çarşamba, 12:05 am tarihinde, Katharine Thayer yazmış:
> 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
yazmı�:
>>> 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... (!?