Re: Uranotypes



            Yes, Poly Vinyl Alcohol.  I found the UN soln, even without the dichromate, VERY "fluid" so it soaked into the paper, even the COT 320.  Those few drops slow down the soaking in so, though it DOES soak in a bit, it stays near enough the surface to be exposed.  No idea about the PVA's specs.  I asked a friend at a local lab and this is what she gave me.

            It sounds like you are taking proper precautions!




From: [] On Behalf Of Jim Patterson,
Sent: Sunday, May 30, 2021 10:06 AM
Subject: Re: [altphotolist] Uranotypes


Hi Bob,

Thanks for the info.  I have potassium dichromate powder so I can make any strength.  What is the PVA purpose.  I assume that is polyvinyl alcohol solution.  I have many types of powder including a commercial solution.  Is it medium weight, partially hydrolyzed? And what %w/v?


I am an Occupational Medicine MD so I am aware of the risks.  I added the calculated amount of distilled water to the bottle the UN came in rather than pour out the powder to weigh.  It is stored in a brown glass bottle in a steel container.


I use nitrile gloves, rubber apron, respirator, and safety glasses.  Darkroom has cross flow ventilation.


On May 30, 2021, at 8:41 AM, BOB KISS <bobkiss@...> wrote:


            Uranyl Acetate seems to be available at the same supplier from whom I buy my uranyl nitrate.  Pse suggest concentration of sensitizer solution.  IIRC Bob Schramm's recommended concentration for UN is near saturated.  I would be happy to try it.




From: [] On Behalf Of Mike Ware
Sent: Sunday, May 30, 2021 7:37 AM
Subject: Re: [altphotolist] Uranotypes


The use of uranium salts as printing photosensitizers goes back to C.J. Burnett of Edinburgh in 1855, when he exhibited images in uranyl ferrocyanide, and in 1857 when he obtained gold images. This is a sub-plot in my book Gold in Photography: see pp. 97-99 for many references to the original literature. Silver, palladium, and platinum images have also been obtained this way.

A couple of my chemistry project students at Manchester looked at photosensitizers employing U(VI) salts in 1985/6 and concluded that uranyl acetate was the best of several possible salts, including the nitrate. We made some nice gold prints this way. You may find it worthwhile trying the acetate for your Uranotypes.
Mike Ware

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