Re: (Gum) Tonal scale

Hmm, this brings out another source of confusion when talking about
tonal range.... I thought Yves was talking about density values rather
than number of steps. You can get the same number of steps with a
light-valued pigment as with a dark-valued pigment, for example, by
choosing the pigment concentration and exposure to achieve that result,
but the density range between the darkest and lightest step, and the
density of the darkest step, will be considerably different for the
two pigments.
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 12:21:11 2005