U of S | Mailing List Archive | alt-photo-process-l | Re: VDB Color

Re: VDB Color



Recently I experimented with a citric acid first bath and noticed a loss of Dmax. Perhaps I mixed too much citric acid into the solution. Christopher James mentions a pinch. Did I equate a pinch with a spoon (which is what I would use with the Ware cyanotype)? I need to test and compare citric acid at the beginning and end but why would it matter when the citric acid bath was applied? EDTA is applied at the end of end of processing palladium and ziatype and citric acid is the first step in new cyanotype (Ware). Would EDTA be a more effective iron solvent?

How long would yellowing highlights take to show up? My earliest prints using this workflow are  from Spring of 2008.

The paper I have is relatively lightweight (compared to Aquarelle); a kozu unryu.

-francis

On Thu, Aug 6, 2009 at 6:13 PM, Don Bryant <donsbryant@gmail.com> wrote:

Francis,

 

After reading through your processing outline for VDB I think you have some potential flaws to your workflow. Namely that in step 1 the tap water clearing should be replaced with a weak citric acid bath. You list your use of a citric acid clearing bath as step 8 which is too late in the workflow to ensure the removal of residual iron compounds.

 

I use two discrete citric acids baths before a brief tap water wash prior to toning and then tap water rinse before fixing. Of course there are many variations related to toning but I think the critical first steps of clearing need to be done with a wash that is definitely acidic to prevent trapping ferric iron compounds in the paper..

 

 

Don Bryant  

 


From: francis schanberger [mailto:frangst@gmail.com]
Sent: Thursday, August 06, 2009 8:02 PM
To: alt-photo-process-l@usask.ca
Subject: Re: VDB Color

 

Joao,

First of all I would say that your fix is too strong for my liking and done for too long. Of course you may compensate by increasing your exposure (to a point).

Your color variation could be the result of humidity or the "freshness" of the hypo. I use a 3% hypo and have to admit that I haven't tested it to see when it has built up too much silver. My working rule is to change the hypo after doing eight 12" x 9" prints or four 16" x 12". I cover the hypo in its pitcher overnight if I haven't met that quota. If you want more consistency consider adding another variable to your process. Toning with gold chloride / thiocyanate before the fix. I get very consistent color when I incorporate this step.

Also if you have found VDB has suddenly turned ugly on you and no longer is returning the love you have for it, mix up some fresh VDB and let it age 48 hours.

Here is my working method: Humidity between 60 - 70 percent

1. Tap water. Pre-rinse exposed print in tap water (face down is something new I've been trying). Make sure the emulsion side of the print avoids the bottom of the tray.

2. Gold toner. Tone with gold chloride / ammonium thiocyanate. (still trying to resolve the palladium toner's effectiveness)

3. Tap water. In between rinse.

4. Hypo. For 45 - 60 seconds. 30 grams per liter although I mix up 60 g in 2 L for a work session.

5. Tap water. In between rinse.

6. Hypo clear. Yes, I'm still using Sprint Fix Remover. Ever since reading Sarah van Keuren's Non-Silver Manual.

7. Tap water. In between rinse.

8. Citric acid to get rid of any or as much of the remaining iron. Two minutes.

9. Tap water. Final wash. Ten minutes.

Hypo is an important step in resolving color, image density, and stability. Don't ask me how it works. You should notice an initial darkening of the image which is a pretty good preview of your dry down. Too long and you bleach away density from all areas of the print. Poorly paraphrasing the Christopher James book: silver links up in the hypo stage. I notice a gradual browning of my hypo which settles to the bottom over several days which may be iron liberated during the hypo stage. By itself water is not an efficient silver (chloramine) chloride solvent.

Contrast: There is a contrast formula in the James book. Liam Lawless method utilizes a mixture of ferric citrate and ammonium ferric citrate in the Part A. Don't ask me how to use it. I adjust my contrast at the stage of creating negatives since they are inkjet transparencies. There's also the option of adding 10% potassium dichromate to the sensitizer for increased contrast.

I don't bother acidifying the step 1 water with citric acid. It will remove a little bit of the iron and decrease the intensity of brown in the final print.

-francis schanberger

On Thu, Aug 6, 2009 at 3:54 PM, Joao Ribeiro Globo <ribeiro.joao@globo.com> wrote:


Hi,

I'm doing VDB on Arches Aquarelle.
I get different colors sometimes, usually dark brown but also reddish brown sometimes.
Is there a way to control this?
Is there a way to control contrast of the VDB?
Process:
Hake brush to apply VDB
Expose
Wash in plain water for 5 min.
Fix in 5% hypo bath for 5 min.
Wash and dry.

Another question, if I wash the copy to get rid of the VDB solution, why do I have to fix?
There is no more silver in the paper after washing, is there?
Thanks in advance,
Joao





--
francis schanberger

www.frangst.com




--
francis schanberger

www.frangst.com

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