Re: (Gum) Tonal scale

On Dec 1, 2005, at 5:58 AM, Katharine Thayer wrote:

>
> On Nov 30, 2005, at 9:46 PM, Judy Seigel wrote:
>
>>
>> I didn't understand much of the discussion about printing clear gum
>> arabic, partly because I didn't understand it, partly because I
>> didn't think I needed to understand it, and partly from suffering
>> from turkey poisoning. But I think one point needs to be made -- or
>> repeated: Results with plain gum arabic and dichromate without
>> pigment will NOT replicate results *with* the pigment. Or let me
>> correct that to say, I doubt that they would or could.
>
> Hi Judy,
> Of course; and I think I've made that point several times, but perhaps
> not clearly enough, in discussing all the different ways that pigment
> can affect the tonal scale. My point about the unpigmented gum was
> to emphasize that while the pigment does provide the tonal scale, it
> does not participate in the reactions which constitute the response to
> exposure, so unlike silver printing and many other photographic
> processes, with gum you cannot draw a curve relating exposure to
> *density of reaction product* to tonal scale. Hope that's clear as
> unpigmented gum,

Compare the above paragraph to the edited version of it quoted below:

> On Dec 1, 2005, at 11:02 PM, Judy Seigel wrote:
>
>>
>> On Thu, 1 Dec 2005, Katharine Thayer wrote:
>>
>>> ... My point about the unpigmented gum was to emphasize that while
>>> the pigment does provide the tonal scale, it does not participate in
>>> the reactions which constitute the response to exposure, so unlike
>>> silver printing and many other photographic processes, with gum you
>>> cannot draw a curve relating exposure to *density of reaction
>>> product* to tonal scale.
>>
>> Actually this calls to mind an expression I've used in trying to
>> explain the process -- I say the action is the gum, dichromate, etc,
>> and "the pigment is just along for the ride." But in fact, it occurs
>> to me that the character of the passenger can make a large difference
>> also -- if he weighs 300 pounds, if he keeps opening all the windows,
>> if he throws rocks at the bicycles passing by, etc. (Or "she," of
>> course.) That is, we do know that the particular pigment affects
>> behavior -- even if just its opacity.

I was thinking people just didn't get what I was saying, no doubt
caused by my failure to be clear enough even yet. But when you strip
off the sentence at the beginning of the paragraph which explains how
important I think pigment is, and then respond to the truncated
paragraph as if my position was that pigment has no relevance, that
seems to approach close to wilful distortion of my position.
Katharine
Received on Sat Dec 3 13:31:46 2005