[alt-photo] Re: Gum Printing: Looking for some wisdom

Thu Mar 7 17:23:57 GMT 2013

Thank you all for the great responses.

I went online this morning and purchased chris's book.  I am looking
forward to getting some new information.

Just for some more info on my process...
I am brush coating
Developing in room temp water checking every 20 minutes and changing water
if it is yellowish.
This last test I soaked overnight, after an hour and half of soaking I was
anxious to get home...

Here is my current plan:
Mix new ammonium dichromate 10% solution and use winsor blue 24ml to
1/2gram (as per the result of the Keeper's of the Light dot test I
performed yesterday).
Stay tuned I should have results in a few hours.

Thank you!
Jennifer Gioffre
Teaching Support Specialist

Architecture Art and Planning
Cornell University
120 Tjaden Hall
Ithaca, NY 14853

Office: 607-255-4207
Fax: 607-255-3462
jmg393 at cornell.edu
darkroommanager at cornell.edu

On 3/7/13 12:13 PM, "Jack Brubaker" <jack at jackbrubaker.com> wrote:

>Just for amusement, I have used 30 year old AD solution with no
>apparent problems. That is I got good prints. However I should qualify
>that by saying that was with my working in a very loose manner that
>would shock many on the list who carefully measure and keep records.
>It was a saturated solution with precipitation at the bottom.
>
>Jack
>
>
>
>On Thu, Mar 7, 2013 at 11:58 AM, Diana Bloomfield
><dlhbloomfield at gmail.com> wrote:
>> P.S.  I'll second the suggestion that you should by Chris's book-- a
>>wealth of information.  And my exposure times for gum are typically 4-7
>>minutes.
>>
>> Diana
>>
>> On Mar 7, 2013, at 11:53 AM, gumprint at gmail.com wrote:
>>
>>> Greetings Jennifer,
>>>
>>> I have been making gumprints using a bank of 6 BLB 4" from the contact
>>> frame with both analog and digital negatives. My exposure time range
>>>from
>>> 30 seconds to 7 minutes, never more.
>>> In looking at your pigment dilutions I found them to be much different
>>>from
>>> what I have been using (since 1978). I am one of those people who
>>>tested
>>> all the Windsor and Newton tubed pigments (with dichromate) to
>>>determine
>>> staining and maximum pigment ratios. An emulsion made with 1/2 gram to
>>>60
>>> ml of gum arabic is, to me, quite dilute. For lamp black I would
>>>typically
>>> use 1/2 gram to 10 ml of gum mixed 1:1 with a 15% solution of ammonium
>>> dichromate and use Fabriano Artistico (post factory sized) or Soft
>>>press
>>> FA. (I have to admit here that I never use WN lamp black because for
>>>me it
>>> stains when over 1/2 gram and at 1/2 gram it is too thin.) I develop
>>>in 80
>>> degree water for 15 minutes (face up for one minute first), changing
>>>the
>>> water 4 times for total of 1 hour.
>>>
>>> As an aside, nearly all the pigments I use are 1/2 gram to 1 gram per
>>>10ml
>>> gum, which I mix using a glass mortar and pestle so I am sure the
>>>pigment
>>> is in suspension. There are a lot of variables in printing gum and
>>>some of
>>> what you have not said may also be leading to your unusual results
>>>such as
>>> development water temperature, length of development, humidity, coating
>>> method and thickness, etc.
>>>
>>> If your dichromate is dropping crystals it is likely over saturated.
>>>30% is
>>> a saturated solution with ammonium dichromate and it will drop out if
>>>under
>>> 65 degrees. I would warm it in a hot water bath, not heat it directly.
>>>
>>> With regard to the tanning effect, I think you may be seeing the gum
>>>arabic
>>> that has been rendered insoluble from the lengthly exposure.
>>>
>>> I hope this helps. Feel free to write back if any of this is unclear.
>>>
>>> Best,
>>> Carole Hollander
>>>
>>>
>>>
>>> On Thu, Mar 7, 2013 at 10:58 AM, Darkrooms, Department of Art <
>>> darkroommanager at cornell.edu> wrote:
>>>
>>>> Hello all,
>>>>
>>>> I have been following this list serve for about two months now and
>>>>what a
>>>> wealth of knowledge you all have!  I am hoping that you might give me
>>>>some
>>>> words of guidance as I attempt to tackle gum printing.  Before I ask
>>>>my
>>>> questions I would like to give a little background on how I will be
>>>>using
>>>> this process and where I amŠ
>>>>
>>>> I am the Photo Technician at Cornell University and we have been
>>>>teaching
>>>> an alternative processes course using Litho and digital negatives.
>>>>This
>>>> past winter break I started using the quad tone rip and we are adding
>>>>Gum
>>>> printing to the list of processes covered.  I have had fantastic
>>>>results
>>>> creating negatives with Quad Tone RIP for Cyanotype, VanDyke Brown
>>>>and NA2
>>>> Platinum.  I am just starting the process with Gum and having only
>>>>dabbled
>>>> in gum briefly about 3 years ago I am getting a little tripped up
>>>>with the
>>>> process.
>>>>
>>>> So far I have completed the dot test that is outlined in the Keeper
>>>>of the
>>>> light to determine Pigment to Gum ratios for each color I would like
>>>>to
>>>> use.  I have completed this on both the Fabrino Soft Press (un-sized)
>>>>that
>>>> was discussed a few weeks back and Rives BFK sized in Gelatin and
>>>>hardened
>>>> with Glyoxal.  The dot test looked great and I am now moving on to
>>>> determining a base time for printing with pictorico.  I am starting my
>>>> tests with Winsor Newton lamp black 1/2g in 60ml of gum arabic mixed
>>>>1:1
>>>> with  Potassium dichromate and another with Ammonium Dichromate.  I
>>>> completed a time test with a strip of pictorico using 4 minute
>>>>increments
>>>> up to 32 minutes with each sensitizer on both Fabrino and Rives
>>>>paper.  I
>>>> am using a homemade exposure unit that consists of a bank of closely
>>>> spaced black light UV florescent tubes approximately 3 inches from the
>>>> exposing area.  The tests on both papers took overnight to completely
>>>> clear of the brownish coloring.  From what I have read some people are
>>>> able to obtain an exposure on a light table in less then 10 minutes.
>>>>My
>>>> tests show a distinct separation between the Base+Fog of the
>>>>pictorico and
>>>> the uncovered areas of the print up through 32 mintues.  On the
>>>>Fabrino
>>>> paper with Ammonium Dichromate at 32 minutes this difference is just
>>>> barely noticeable and my thought is that at about 35 minutes I
>>>>surpass the
>>>> base+fog of the pictorico.  After about 12 minutes on all test some
>>>> tanning is appearing.  If I were to go with a 35 minute exposure
>>>>tanning
>>>> is sure to be visible.
>>>>
>>>> My questions are:
>>>> 1.  Should I try for longer exposures to see if I can obtain an
>>>>exposure
>>>> sufficient to hide the Base+Fog of the pictorico and if so is there a
>>>> remedy to the tanning?
>>>> 2.  Should I adjust my mix of sensitizer?  I have mixed the Potassium
>>>> Dichromate in a way that it has a large amount of precipitated chem
>>>>unless
>>>> heated to almost 100F (this was done at a professor's request).  I
>>>>mixed
>>>> the Ammonium Dichromate as outlined in Sarah VanKeuren's Non-Silver
>>>> Manual, placing chemical in a graduate to reach the 1oz line and
>>>>adding
>>>> water to 10oz.
>>>> 3.  Or do you have any other suggestions?
>>>>
>>>> Thank you in advance for reading this long email and I am looking
>>>>forward
>>>> to any words of wisdom you have to offer.
>>>>
>>>> Best,
>>>> Jennifer Gioffre
>>>> Teaching Support Specialist
>>>>
>>>> Architecture Art and Planning
>>>> Cornell University
>>>> 120 Tjaden Hall
>>>> Ithaca, NY 14853
>>>>
>>>> Office: 607-255-4207
>>>> Fax: 607-255-3462
>>>> jmg393 at cornell.edu
>>>> darkroommanager at cornell.edu
>>>>
>>>>
>>>> _______________________________________________
>>>> Alt-photo-process-list | http://altphotolist.org/listinfo
>>>>
>>>
>>>
>>>
>>> --
>>> *Carole Hollander*
>>> _______________________________________________
>>> Alt-photo-process-list | http://altphotolist.org/listinfo
>>
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