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<< Lancair Builders' Mail List >>
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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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Please send your photos and drawings to marvkaye@olsusa.com.
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