U of S | Mailing List Archive | alt-photo-process-l | Re: two questions about gum

Re: two questions about gum

It is more accurate to say that PDN turns off the Adobe Color Engine,
which maps a profile from the file's color space to the printer's color
space. All the systems still do use a driver, whether it be the Burkholder
method, the PDN system or the QTR system.

There is still some black box stuff going on between the file being sent
to the printer and how the driver decides to lay down the ink on the
substrate. Whether you use an Epson or Canon or whatever, you still must
have some piece of software that takes the numbers in the file being
printed and translates them into instructions to the printer for pushing
ink out of the nozzles.

Some systems like OPM/IJC or QTR allow you to access the internals of the
driver and fiddle with the ink output at the level of each individual
color. Others, like the printer drivers that the PDN system must use, just
rely on the fact that whatever is going on in the driver is repeatable and

All the systems can clearly produce excellent results in knowledgable hands.


> I'll chime in with my two cents here with Marek.  Curves should be taking
> care of all things--either a too dark print or a too flat print.  If not,
> the curve is wrong.  And, if the printer's adjustments are not turned OFF,
> then the printer will also alter the curve that one makes.  That's why the
> PDN system does not use the printer driver; it's like you go to all this
> work to make a curve and then send it to the printer and the driver mucks
> it
> up on the fly--usually it comes out a paler version of the negative which
> would in turn print too dark.
> I don't know what your printer is, but in my Epson 2400 I have to select
> and then "no color adjustment".  In the 4000 and other printers there are
> TWO places you have to select "no color adjustment"--but that's on a Mac
> driver and Macs have to be told things twice because they are dumber
> (heheheheheh).
> But, as Ron Reeder pointed out at APIS, to each his own--three systems of
> curve making, download Dan Burkholder's curves who has done all the work
> in
> the trenches for you, use the Reeder method which utilizes the printer
> driver, or use PDN system which turns it off and makes the curves WYSIWYG.
> That is a crass over simplification of diginegs but maybe makes the point
> I
> am trying to say. (But, Dan, do you have curves for gum?)
> But one more point, Charles--or was it Loris--magenta/red is a really
> strong
> pigment, unless it is PR209 which is sometimes called quinacridone red or
> q
> coral or whatnot--it is a fairly weak red albeit beautiful corally red
> really nice for some images.  But in general, magenta and thalo are strong
> colors and need to be cut down in the first place BEFORE curves are made
> to
> make sure you won't go too dark when the layered colors are finally done.
> For instance, I may use the 1/4 the magenta that I do raw sienna, or even
> less.  It's that different.  I figure out my mixes of each color that I am
> going to use before hand and then always use that and develop my curves
> and
> times for those mixes.  So I standardize first, get that practice correct,
> and then I can be loosey goosey about it, cut my pigments to real low
> saturation, etc.  However, I can't say I have ever used time to vary a
> print
> because, as Mark reminded us, you're not gonna get your highlights printed
> in, and why would you want to print a layer of just shadows when your
> print
> is too dark in the first place? Unless it is your highlights that are too
> dark, too, I suppose, might be the scenario.
> All of this said, there are gum printers who adjust their process to plain
> old uncurved negatives for the last century and a half and have beautiful
> work, so to each his own--there are many ways to skin this cat.  When I
> started teaching gum this last semester, I first taught them with uncurved
> all ink negs and even tho the shadows were blocked up, they produced some
> pretty amazing first gum prints.  These higher tech ways are only
> necessary
> if the original practice is not working well. There is a pretty major
> difference between my gum prints before and after curves when laid side by
> side, but if not seen side by side I don't think the buying public would
> say
> my pre-curve prints are nasty.
> Chris
> ----- Original Message -----
> From: "Marek Matusz" <marekmatusz@hotmail.com>
> To: <alt-photo-process-l@usask.ca>
> Sent: Wednesday, September 26, 2007 7:18 AM
> Subject: RE: two questions about gum
>> Charles,
>> I would say you should adjust your curve and not cut your pigments.
>> Cutting down on pigment will result in whimpy and grey looking print.
>> Adjust your curve so that you add ink density to the middle tones
>> resulting in lighter CYM printed layers. Longer development would help
>> as
>> well. I like to have my negatives for tricolor gum to be a bit more
>> contrasty then they would be for a single coat gum and each layer when
>> printed somewhat ligher then for a single coat gum. Am I making sense
>> here?
>> My 3c for the day
>> Marek> Date: Tue, 25 Sep 2007 20:25:18 -0700> From:
>> kthayer@pacifier.com>
>> Subject: Re: two questions about gum> To: alt-photo-process-l@usask.ca>
>> >
>> Charles, I'd need to see the print to say how much to reduce the >
>> pigment. As a stab in the dark (so to speak) I'll say if it's > really
>> really dark, then try cutting the pigment by half; if it's > just sorta
>> dark, then a quarter.> kt> > > On Sep 25, 2007, at 6:57 PM, ryberg
>> wrote:>
>>  > > Folks,> > Since it is blown highlights plagueing me, I'll try again
>> with > > reduced pigment. Any guess as to how much? Half? Quarter? Do >
>> >
>> you suppose I will need a new curve?> > Thanks Charles Portland Oregon>
>> >>
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