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

Re: Paper negatives- Ink Selection

  • To: alt-photo-process-l@usask.ca
  • Subject: Re: Paper negatives- Ink Selection
  • From: Keith Gerling <keith.gerling@gmail.com>
  • Date: Wed, 15 Oct 2008 10:43:24 -0500
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Hi Loris,

My gums require 15 minutes with oiled negatives.  I would really like
to reduce this.  Also, cyanotypes made with the same oiled negatives
require exposure times of 30-45 minutes.  How does this compare with
others?  It seems pretty long.


2008/10/15 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
> yazmıÅ&#65533;:
>>>> 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... (!?