New Vandyke Brown solution stand time

ColinRH

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Most, or perhaps all, VDB recipes state that after mixing the solution it should mature/ripen for 24-48 hours.

Is anyone able to say why that is? I have used it straight from mixing and it produces images as I would expect. So why do we have to wait?

I think we all know that Alternative Processes are a bit ‘flaky’ at times, so is the maturing time something of an absolute necessity? It may be that if it is not permitted to stand for that time then some unwanted chemical reaction within the paper occurs which would only be apparent some long time later – perhaps years. But……...

Any ideas?



I’ve done my very best to find an answer from Mike Ware’s writing but it is way beyond me.
 

glbeas

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I have noticed the VDB sensitizer I mixed is silvering the sides of the bottles they are in. Makes me think it should be mixed and used quickly in small quantities.
 

revdoc

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Like a lot of alt-process "wisdom", I suspect this is a piece of advice from someone back in the dim, dark past that gets repeated without much thought. That's why my rule of thumb with alt processes is that if not everybody says it, it's open to question.

I can't see any chemical reason why the solution needs to age before use. The reactions all happen during exposure and processing; nothing has to happen before the Fe(III) is converted to Fe(II) by UV light.

Personally, I keep my VDB solutions in 3 dropper bottles and mix just before coating, and it works every time. When I started out I used premixed solution, and that worked too, but it deteriorated over a couple of months. Separate solutions stay good for far longer.
 

koraks

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This is exactly my experience as well. I also use separate solutions, which last indefinitely and are always good to go.
 
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ColinRH

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Revdoc and Koraks, thanks for your confirmation of the procedure.

I’ve been trying to find out why I have been having a problems with my VDB’s and decided it was chemistry based. Checking Photrio I found the entry by koraks (thanks) and later your own site and the entry referring to VDB’s. That decided me to mix the 3 chemicals separately and it in doing so have been able to easily substitute new and older chemistry. So far I have only tried silver as I am waiting for the other 2 parts to be delivered. So far its not the silver but having tried this method of mixing separately it really has very welcome benefits.

So thanks koraks and I would recommend anyone else trying VDB to give this method a try.
 

Tom Taylor

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I'm not a chemist but I suspect that the reasoning behind "ripening" is to allow sufficient time for the chemicals to interact and coalesce into a solution. Personally I mix from scratch into 3 separate bottles and once the ferric ammonium citrate has cleared, combine the 3 into a working solution and let sit for a day or two before using. No issues with the resulting prints of which one (toned with palladium) is posted below:



Thomas
 

KenS

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While I have taken to mixing my VDB from 'scratch' over the past number of years (as a means of saving some 'pennies'), I have never experienced any 'difficulty' of any 'precipitation' even after 'some of it' has been used and the bottle is but 'part full'..maybe I am doing a 'something' wrong. (???)

Ken
 
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