Archived posting to the Leica Users Group, 1999/02/18
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Jim Brick wrote:
> Photoflo works because it is a soapy solution with a pH above 7.
So far as I can tell Photoflo is simply nonionic detergent - NP40 or
Triton X-100 or Tween20. It works by decreasing the wash water's
surface tension, reducing droplet formation on the film surface.
If I'm correct about this, Photoflo is neither soapy (soaps are IONIC
detergents), nor does it affect pH. If it did change pH it would do so
by containing a buffer, and this would, I think, tend to INCREASE
spotting because buffers generally are salts.
For several years I've used NP40 instead of Photoflo (I use an outdated
lab stock that I no longer trust for my biochemical work). Seems to work
perfectly.
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Alexey Merz | URL: http://www.webcom.com/alexey | email: alexey@webcom.com
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