[alt-photo] Re: gum curve question
viapiano at pacbell.net
Thu Aug 19 01:49:05 GMT 2010
I would think you would want to use a gelatin-silver curve to get the tones
for the digital interpos, right? Something that looks as close as possible
to a film interpos, and that's usually a non-contrasty weak positive.
----- Original Message -----
From: "henk thijs" <henk.thijs at hetnet.nl>
To: "The alternative photographic processes mailing list"
<alt-photo-process-list at lists.altphotolist.org>
Sent: Wednesday, August 18, 2010 3:17 PM
Subject: [alt-photo] Re: gum curve question
> .......... forgot to mention one important thing: the reason i want to do
> this is the fact that i make my digital negs on non-transparent
> plotterfoil, that means times for gum about 700 secs, for (brom)oil
> printing about 1600 secs and it is not suitable for cyanotype.
> Using it for interpositives with the APHS film my times are something like
> 70 and 160 secs , and i can make tri-color gumprints like Sam does: a
> cyanotype as the cyan-layer.
> On 18 aug 2010, at 22:35, Paul Viapiano wrote:
>> I'm guessing that Henk wants to make a digital interpos to print on to
>> APHS film to make a final neg, thereby eliminating the need to make a
>> wet-step positive.
>> Henk, you could always try this and see what happens. Usually an interpos
>> is made with much less contrast, so that final contrast can be controlled
>> in the making of the interneg. You're looking to make color seps for
>> tricolor this way, right?
>> ----- Original Message ----- From: "Don Bryant" <donsbryant at gmail.com>
>> To: <alt-photo-process-list at lists.altphotolist.org>
>> Sent: Wednesday, August 18, 2010 12:03 PM
>> Subject: [alt-photo] Re: gum curve question
>>> Dear List,
>>> Using the gum-curve via PDN to create digital negatives, the following
>>> question came up:
>>> Cleaning 'old-analogue-stuff' i found still a lot of Arista APHS film,
>>> so i
>>> want to use it.
>>> Making a digital positive and sandwich it with the APHS.
>>> Now i was wondering about what curve to use: the one found with PDN
>>> digital negs is based upon UV-blocking of the ink used by the printer,
>>> for the sandwich 'normal' light is used to obtain the neg.
>>> The question is what curve is to be used for the positive?
>>> Now i tried the following : invert the positive, apply my 'PDN' curve,
>>> invert again, sandwich and the result is a APHS negative.
>>> Gum looks ok, but before going in tri-color printing i am open for any
>>> suggestions :-)
>>> I don't know about everyone else but I'm confused as hell about what you
>>> attempting to accomplish or do. Can you run this by us one more time
>>> with a
>>> bit more clarity?
>>> So sorry to be so dense,
>>> Don Bryant
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