Re: How many gum layers (Re: ferri sesquichlorati)

[Katharine Thayer <kthayer@pacifier.com>]

>  " Otherwise, why not just start with an image, invert it and make  
> a negative of any unknown density without a curve and keep fiddling  
> with it until you get what you want in the print."
>
> Best Wishes,
> Mark Nelson

Well, indeed, why not.   Like Keith, this is exactly my approach and  
as Keith says, it works fine.  And as Chris showed last week, it  
works good for her too.  Her tricolor gum made from inverted uncurved  
channels was cyan-biased, but that's not a function of the curves,  
that's a function of the  selectiion of pigment concentration of the  
three pigments in relation to each other.  So I guess my answer to  
Mark's question "why not?" is,  beats me!  Seems like a perfectly  
reasonable approach to me.

But since Charles posted the link for ChartThrob yesterday, I've been  
playing around with generating curves some myself, and like Keith, I  
have to say, so far I like the "no curve" approach better too.

Recently, Mark, you said that a beginner could save a lot of time,  
money, and materials by investing in a system for generating curves,  
or better yet, two systems.   At the time, that didn't make sense to  
me, because the time and materials you "waste" in the beginning  
learning to print gum are "wasted" in the process of learning to  
print gum, not in the process of generating negatives, and you still  
have to learn how to print gum, no matter how you generate your  
negatives. So I'm not sure how it would make any difference.   And  
besides, the way gum works, there's very little waste; there's almost  
no print that can't be salvaged; pigment stain is the one exception,  
and curves or no curves don't have any bearing on pigment stain.    
But I didn't think there was any point in arguing further, so I let  
that thread die without saying so.

But now, after an evening of printing value templates,  I have to say  
I think the savings are in the other direction; you save more  
materials by printing gum. At least when you're actually printing  
images, you have a print to work with and do something with, and  
chances are you can do something with it, even if you didn't get it  
"right" on the first printing.  But a template of value patches is  
just a template of value patches.  And if I was really going to do  
this, I'd have to do it for every single different pigment I ever  
use, at every concentration I use it at, at every environmental  
condition (humidity, particularly).... I would be doing nothing but  
printing templates for the rest of my life, and there's not a thing  
you can do with the stupid things, except generate curves.  Talk  
about waste of materials!  I'd rather be printing gum.

I can't say yet whether the resulting curves would be an improvement  
over the uncurved negatives; I'm not even there yet.  Will report in  
due time with a comparison.
Katharine





> On Oct 25, 2006, at 9:27 AM, Keith Gerling wrote:
>
>
> Well, Mark, that is exactly my approach and it does seem to work.   
> However, having been challenged by recent workshop participants as  
> to why NOT use a curve of some kind I admit that I have been  
> fiddling around with curves lately and have found that the curve  
> that works best for me is a straight line, i.e., no curve at all.   
> So I'm curious.  Are there list members out there that DO use  
> curves for gum printing?  Might one of them be persuaded to share  
> their curve with me so that I can try it?  I'll figure out some way  
> to repay a kind soul for this generosity.
>
> Keith