From: RWolf99@aol.com
Message-ID: <24.9b09471.26d7e728@aol.com>
Date: Fri, 25 Aug 2000 11:13:44 EDT
Subject: Re:  Methylene Chloride or Acetone?
To: lancair.list@olsusa.com
Reply-To: lancair.list@olsusa.com
Mime-Version: 1.0

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In a message dated 8/24/0 10:54:41 PM, you wrote:

<<Here's a simple question... is it worth the trouble and expense to use
MC as opposed to acetone for surface prep & cleanup? >>

I cast a very strong vote for Methylene Chloride.

When I was forced to work outside the aerospace field for a couple of years, 
I worked for a company developing zinc-air batteries for electric cars.  We 
essentially were doing chemical engineering, and had all kinds of chemicals, 
solvents and other stuff to play with.  One of the things we needed to do was 
to clean and degrease the copper anode plates on the battery cells.  I could 
take a squirt bottle of acetone and loosen the dirt/grease and rub it off 
with a rag, or I could squirt methylene chloride on it and watch the crud 
just sluice off, leaving a pristine surface with no rubbing required.  The 
methylene chloride also evaporated much faster than acetone.

As an aside, even though we did all our work in chem lab fume hoods, I would 
come home on occasion with a pounding headache.  I was able to isolate this 
to acetone.  Once I stopped working with acetone the headaches went away.  
But that's probably just me -- others don't seem to have this sensitivity.

I'm very careful with the methylene chloride.  I open the garage doors every 
time I use it and let the garage air out.  You do NOT want this stuff hanging 
around -- one drop on the floor will fill up your garage to the threshhold 
limit value (TLV) for an eight-hour exposure.  If you air out the garage, the 
problem is gone.  (TLV is for long-term exposures.)  I use heavy duty gloves 
when working with MC but only use latex when working with the epoxy.  I have 
a 1 gallon storage bottle of MC, but dispense it into a little four ounce 
glass jar (swiped from the chem lab) that I carry around when I wipe off the 
parts to be bonded.

My opinion -- based on observations -- is that methylene chloride is a 
superior cleaner and worth the extra expense and trouble.  I've spent 800 
hours of hands-on labor and used only two gallons (or was it three?).

- Rob Wolf
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