RE: Magic Wash

Our labs stores our de-ionized water in polypropylene carbouys, but then
again we use about 5 L a day so it cycles through pretty quickly.  If
the water sits around more than a few months, it will extract stuff from
plastic.  Our HPLC grade water is stored in glass to prevent it from
picking up more than a few PPM of metals and other "contaminants".  In
our RO (Reverse Osmosis) system, water in the reservoir can increase in
conductance (a measure of the ions present) from 4 microsiemens to over
100 microsiemens over night.  Our standard to consider water de-ionized
is 20 microsiemens.  Admittedly this is probably a much higher standard
than the average painter needs, but I was considering the fact that if
someone buys a gallon of such water, they probably aren't using it up in
week or two, and it may remain around for months.  For such long-term
storage, I would definitely recommend glass.

Anecdotal evidence - when you buy a new plastic canteen or tupperware,
place some water in it overnight at room temperature.  If you taste the
water in the morning, it will often have that "plastic" taste to it.

--Binhan

> -----Original Message-----
> From: John Sowerby [mailto:sowerbyj@fiu.edu]
> Sent: Friday, June 28, 2002 1:03 PM
> To: gzg-l@csua.berkeley.edu
> Subject: RE: Magic Wash
> 
> 
> At 12:59 PM 6/28/2002 -0600, you wrote:
> >Some grocery stores offer carbon and ion filtered water 
> which is the next 
> >best thing.	You can always just boil some up and tap the 
> distillate from 
> >the pot lid into a funnel and into a bottle.  Time 
> consuming, but not 
> >difficult to do.  Remember to store in a glass bottle, as 
> distilled water, 
> >lacking a lot of ions and minerals will draw out chemicals, 
> ions and stuff 
> >from plastic, metal and non-glazed ceramics.
> 
> Not particularly. Most labs store distilled water in plastic 
> containers.
> 
> John S.