Re: (Gum) Tonal scale

Yves,

You may expect to get *about* 6 steps of a Stouffer 21-step scale
printed on average with a good exposure for gum. (This works out to be
about a 3-stop range.) This will vary with pigment and paper, etc., as
well as pigment concentration and duration of exposure as David
suggests. You will probably also find that even using the same pigment
mix, the density gain of later coats never quite matches the first coat
density increase due to the effect of the first layer making the surface
slicker and acting as a size for later coats. As the paper gets
slicker, the gum does not adhere as well, OTBE.

"Your mileage may vary."

Joe

>>> davidhatton@superonline.com 11/28/05 10:31 AM >>>
Hi Yves,

It's my understanding that at least three exposures are necessary for a
full tonal print. Could be more or less but it goes something like

Highlights :- little pigment + long exposure - say 2 minutes
Mid tones :- More pigment + less exposure - say 1 minute
Shadows :- Max pigment + least exposure - say 30 secs.

Understand this is the principal not necessarily the practice.

Hope this helps

David H

Yves Gauvreau wrote:
> Hi everyone,
>
> I wonder if someone knows what kind of tonal scale (range) one
> can expect with gum printing when using a certain number of exposure
for
> the same print???
>
> I assume density will build up, thus increasing the range between the
> white of the paper and the darkest areas. I suspect also that these
> multiple exposure are not linearly additive meaning that if I get a
> density of say 1.0 somewhere on the first exposure I wont get 2.0 with

> the next exposure.
>
> Thanks
> Yves
>
>
>
>
>
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Received on Mon Nov 28 11:07:54 2005