From: dr. jack correia <jcorreia@fiona.umsmed.edu>
  To  : rasmb@bbri.eri.harvard.edu
  Date: Thu, 9 Jun 94 10:53:30 -0500

Re: Damaged windows

HELP!!

     During a recent short column run with buffers containing NaF we
 experienced precipitation problems between pH 3 - 6 that stained the
windows with a cloudy film.  Acid soaking does not remove it.  Are there 
any suggestions for reclaiming these windows - base?  repolishing and if
so where can it be done?  Is the damage irreversible? 

    These are the new high transmittance windows for the XL-A ($300 per).
I have never seen this kind of problem while working with the Model E.  Is
this a problem with all windows?  Is the damage always irreversible?  Will
any buffer or protein precipitation cause this to happen?  

     NaF "was" being used as a kosmotrope to promote protein association!
The solubility of NaF appears to be pH dependent being higher above pH
7.

     JACK