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

[Marek Matusz]

A quick way to test dichromate soluiton is to take unexposed and dry test strip and develop it. You should get a clear white paper. I am not familiar with your test negative. Stoufer tablet is most common and most universally used. If your negative had enough density of say 1.2 to 1.4 then you have overexposed your test strips. 

What printer are you going to use. I print my negatives with qtr on Epson 3800 and can offer some initial settings

Marek

Sent from my iPhone

On Mar 11, 2013, at 1:27 PM, "Darkrooms, Department of Art" <darkroommanager at cornell.edu> wrote:

> Hello all,
> 
> I am reporting back with the tests I made last Friday.  I was going to mix
> new Ammonium Dichromate, but I did not have a new bottle.  So, I decided
> to retest my original test of Ammonium Dichromate.  You can view the tests
> here: http://www.flickr.com/photos/93779173@N03/sets/72157632974249458/
> 
> I think that I now have a good jumping off point with these tests.  This
> week I hope to work on the calibration of the QuadTone Rip negative.
> 
> Thank you for your help!
> 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
> 
> 
> 
> 
> 
> 
> 
> 
> On 3/7/13 1:56 PM, "Kees Brandenburg" <workshops at polychrome.nl> wrote:
> 
>> Hi Jennifer,
>> 
>> As we are talking about gum, let's not forget this variable. What gum
>> arabic do you use? Premixed or self mixed, and at what concentration and
>> baumé? I'm using a 14-14,5 baumé self mixed gum. This is about 26-26,5%
>> 
>> Looking at your exposure times for cyano and van dyke, compared to mine
>> (6 and 4min) I would say that you would end up somewhere around 10
>> minutes with your bank of UV and normal gum sensitivity. I find your
>> pigment concentration rather low. With 'normal' strenght gum I am using 1
>> gram per 20ml gum for winsor blue and lamp black on gelitin/glut sized
>> paper and never see any stain.
>> 
>> With dichromate I'm a 'replenisher'. When the bottle seems to empty with
>> a coming workshop or project, I make some new and fill the bottle up.
>> From time to time it stands for several weeks or more.
>> 
>> kees
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