Re: (Gum) Tonal scale

Hmmm, here's another potential source of confusion. I thought Yves was
talking about density range and particularly about DMax, which to my
mind is a different issue than number of stouffer steps that will be
printed. You could get six steps in either a light yellow or a black,
for example, by choosing the pigment concentration and exposure to
yield that number of steps, but the tonal distance between the steps
would probably be different; the tonal range between the darkest and
lightest values printed would likely be longer for the black than for
the yellow, and the darkest value printed would certainly be
considerably darker for the black than for the light yellow. So the
number of steps, while useful for judging desired performance for any
one printing, doesn't tell you much about density (meaning in this case
darkness of tone) does it?
kt

On Nov 28, 2005, at 9:09 AM, Joe Smigiel wrote:

> 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 12:29:15 2005