[alt-photo] Re: casein on metals

[Mark Nelson]

Look at how the people who do photogravure clean copper if you are looking for a really good method. 

Mark Nelson
www.PrecisionDigitalNegatives.com
PDNPRint Forum @ Yahoo Groups
www.MarkINelsonPhoto.com

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On May 5, 2011, at 1:11 PM, Peter Friedrichsen <pfriedrichsen at sympatico.ca> wrote:

> I heard mention of casein as being a candidate for coating on metal...I think it was Marek, so I thought I would pass on my experience.
> 
> I have successfully coated, exposed and developed casein+dichromate on copper, aluminum, and even glass but there are challenges:
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> First, the metal must be very clean. I clean the surface with steel wool and a dusting of laundry detergent and scrub for several minutes. Some other cleaners such as dish soap don't seem to work so well. You will know the metal is clean when the water sheets off of the metal after a few minutes of rinsing. It is important that it sheets off, as any beading up will mean that the casein will not adhere sufficiently during development. Coating an even film on metal is a bit trickier than paper and I find that of all things, a silicone basting brush works well. Watch our for any bit of dust as it really shows itself on metal. Cleaning foils may need some other type of approach because they are so thin.
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> Even once you get the coating method perfected, you have a problem if you are hoping for tonality and that is that there won't be any. Lightly hardened casein (grey tones) prefers to stick to itself rather than the metal so it sloughs off and the result is a two tone image with no tones in between. I have heard that tonality can be accomplished with a carbon tissue transfer onto metal using the traditional carbon tissue but that does not involve casein of course. I won't say it isn't possible with casein but that I have not had any luck with it. There may be some type of undercoat that you could apply to help anchor the less exposed casein but I have not attempted it. An undercoat of  powdered silica+hardened casein may do the trick.
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> If anyone has anything to add re metals/glass whether it is casein or even gum, I am all ears.
> 
> Peter Friedrichsen
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