Christina,
I can answer this only halfway theoretically till now. What a buffer is, is defined. But tests must be made. If you take a stronger solution of a crystaline acid like tartric or citric acid, mix it with a crystaline alcaline like potassium hydroxyde and adjust the ph for a final wash, then the influence of aging or something like calcium carbonate for buffering the papers ph should be nihilised simply by the relations of the masses. Thats what buffers are made for.
What I have tried is to fix a cyanotype in an acidic state -- not buffered. To do this I chose oxalic acid to clear the highlights in a final wash (about 0,5 g/100 ccm water if I recall it right). Please see http://www.fotocommunity.de/pc/pc/display/1470653. The picture in the middle shows what a cyanotype looks like when I only dry it after washing with the tap water of Munich. This print says: Im neutral or a bit alcalic. And then see http://www.fotocommunity.de/pc/pc/display/4326586 -- that print got the final oxalic acid bath. I really love this fiery blue and dont see a chance that calcium carbonate in the paper (if it is there) could harm the print because the oxalic is still there.
I think that some of us will end up with several techniques for buffering cyanotypes in some years because a non buffered cyanotype is continuously endangered of changing its color when getting humid. At least it is another artistic dimension to decide whether a print shall be dependant on fortune (not buffererd), fade over the times (alcalic ph) or have a flat (neutral ph) or fiery blue (acidic ph).
Yours
Kai
Received on Sat Apr 22 08:48:33 2006
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