> -----Original Message-----
> From: owner-filmscanners@halftone.co.uk
> [mailto:owner-filmscanners@halftone.co.uk]On Behalf Of Mark Thomas
> Sent: Sunday, March 18, 2001 5:34 PM
> To: filmscanners@halftone.co.uk
> Subject: Re: filmscanners: cleaning neg's, sharpening
> I was surprised to discover how acidic the
> 'pure' water was. The resident chemist gently explained that H20, when
> exposed to air, absorbs CO2 and degrades quite quickly to a carbonic acid
> solution, of about pH 5.0-5.5 I think. (I'm flying by memory here - any
> chemists on the list feel free to correct..)
A pH of 5.0-5.5 is very weakly acidic: neutral is 7.0 and pH is a
logarithmic ratio. Acid rain for example has a pH of less than 4 (10 to 100
times more acidic than what you're talking about). Is 5.5 really dangerous
to film?
Frank Paris
marshalt@spiritone.com
