Re: digital gum negatives

Date view Thread view Subject view Author view

From: Katharine Thayer (kthayer@pacifier.com)
Date: 07/04/01-03:20:21 PM Z


Smieglitz@aol.com wrote:
>
> In a message dated 07/04/2001 21:12:57, holtsg@duke.usask.ca wrote:
>
  If you wish, Photoshop can be
> used to color separate a CMYK image file and print the 4 negatives
> automatically. But, this changes the original RGB file info a bit, so I
> usually just print the 3 channels from the RGB file.

Hi Joe and all,

I agree that RGB separations are preferable to CMYK separations but if I
understand what Gordon's trying to do, he's not working from a colored
image but a BW pinhole image, which he wants to selectively color,
possibly using masks? At any rate color separations shouldn't be an
issue here.

I've always avoided the problem of ink pooling on inkjet transparencies
by using paper negatives when using the inkjet printer for digital
negatives. There's *perhaps* a slight tradeoff in softness but none in
speed; my oiled paper negatives print faster than film negatives.

I've never seen dots on either my Epson photo-series negatives or prints
made from them, even one-coat prints (although I have on negatives and
prints made from Epson printers that weren't photo series printers, like
the 3000). What's interesting is that sometimes there would be a very
fine banding on the negative that I wouldn't see even though I inspected
the negatives by eye before using them. But then when I made the print,
there would be the fine lines in the gum print, and I'd go back and look
at the negative with a loupe, and there they were. It's very annoying to
have to throw out both the negative AND the print but that banding is
one of the few things that can't be corrected. So I'd suggest that
Gordon watch for those. It either means your print heads need cleaning
or the printer doesn't like the media type you've specified.
kt

>
> By all means give the 700 a try. Although the dots will be slightly
> apparent, the gum printing process tends to eliminate them in the print.
> Slight misregistration and dimensional instability of the paper with multiple
> printings and wet/dry cycles tends to fill in the spaces between the dots.
> The result is very acceptable with the multiple gum process (although I find
> the dot pattern distracting in single coat cyanotypes or VDBs.)
>
> You might find lower contrast files will print better. (There seems to be a
> huge jump in %ink output on one end of the scale with the Epson printers.)
> The contrast can be adjusted in Photoshop's curves or levels dialog box
> without clipping the file data. (OTOH, the brightness/contrast control
> eliminates data, so I wouldn't use it.) I also suspect the adjustment curve
> I posted a few days ago will produce better output of the channels on the 700
> or similar printers, although I haven't tested it on models other than the
> 1160 with the quadtone inks. With that system the curve essentially
> eliminates the jump in %ink towards the upper end of the scale and produces a
> low contrast negative that prints about 6 steps of a Stauffer wedge at max D
> with minimum time with a single gum coat.
>
> Let me know if you have any questions as you give it a try. I'd also like to
> see the results.
>
> Joe


Date view Thread view Subject view Author view

This archive was generated by hypermail 2b30 : 08/02/01-11:56:46 AM Z CST