Judy Seigel (jseigel@panix.com)
Mon, 18 Jan 1999 02:51:54 -0500 (EST)
On Fri, 15 Jan 1999, Garet Denise wrote:
> >Step ten is the beginning of the highlights,
> >and I have decent seperation up to step 5, but steps 5-2 show very
> little
> >seperation, with step 1 going quite a bit darker. Does this mean
> that I
> >should consider step 5 to be the end of the wedge? What about the
> great
> >'black' at step 1 - is this just tantalizing me with the impossible?
> In
> >general, I see this often - 4 steps or so of color, and another 4
> with
> >weak seperation and the last one or two with more seperation - what
> gives?
> >
> I have found the same results with the shadows in gum prints, that the
> "toe" of the curve flattens out well before the lower end of the
> response curve. I plain English: it doesn't have as good of
> seperations in the shadows as in the highlights. I hope to compensate
> for this by creating digital negatives and coming up with an
> appropriate calibration curve, but I've spent the last 5 months
> building a new darkroom. Remodel projects are a lot like testing new
> photo processes, they never seem to end.....
As for the "curve" of gum, generally speaking it's quite straight. If
you're getting the bottom blocked up, or a big "hump," odds are you're
either over-exposing, so the bottom steps block up, using too much pigment
so the bottom steps block up, or expecting too many steps for gum. In my
experience, you won't get more than, say 8 steps *at the most* with enough
pigment in them to matter. (If you are just tinting, you can get quite a
few more.) I stuck a step tablet on the side of a cyan coat last week &
got 8 perfectly even steps with enough color to do the cyan, but not to
stand on its own as a full print. It's also possible, Adam, that the
gouache (which I think I recall you mentioning), which is opaque, is
blocking things up even more.
Try thalo blue, which is quite transparent, about 1/2 gram to 3 cc gum, 2
cc water & 3 cc am di. Well, that's from memory, I'll have to check -- but
I must add that the gum is also a factor. The test cited is with RBP gum,
which is always excellent, but hard to get. The Philben gum is slower, but
very very good too.
Also try reducing exposure and/or extending the soak so that there are no
more than two steps blocked at the bottom -- at most.
> >Finally, I never heard much about what printer to buy for making
> negatives
> >suitable for gum - Judy, what are you using now, and do you like it?
> The
> >Photo Dan and Dave's you two are the experts - any real info on the
> >situation?
>
> Seems like lots of people talk about generating negatives digially,
> but either few are actually doing it, or else the ones that are are
> not willing to share details about how they go about it. I, too, will
> soon be in the market for a printer and would appreciate any comments
> (good, bad or otherwise).
>
>
> Garet Denise
> garet@rmi.net
>
>
>
>
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