Mailing List lml@lancaironline.net Message #2573
From: Curtis Krouse <ckrouse@worldnet.att.net>
Subject: Re: methylene chloride supplier
Date: Fri, 11 Jun 1999 17:51:28 -0700
To: <lancair.list@olsusa.com>
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I have been using MC from a paint store.  I paid about $25 for a gallon and
the only other additive that I can determine from the container is acetone.
Since acetone is another solvent that has been approved for use, I thought
that the risk was minimal.  Since it takes a while from cleaning to actual
laying of the laminate, I feel that any flash off of the solvent has been
well done by the time that my layup is actually ready.  Another point is
that in the instructions the preparation is clean first, then lightly sand
the surfaces and then remove the dust by clean rag or vacumn.  I don't think
that any other chemicals are left on the surface after that.  It has proven
to be an effective cleaning agent so far.  Of course, the proof will be over
a period of time or in the air.

My question would be that the MC from the paint store with only an acetone
additive is pretty snotty stuff.  It seems to be very thick and syrupy.  Is
this right?  Since I have never seen MC before I have no idea.  The MC from
the paint store is "paint stripper" and I remember from past experience that
paint stripper is pretty thick stuff.  But, I don't know what pure MC is
like.  Can someone tell me?

Curtis Krouse N753K


[Pure methylene chloride has the viscosity of straight acetone, IOW, it
should run like water.  The MC paint stripper has a thickening agent in
it similar to cornstarch to make it sticky so it adheres to the surface
being stripped and to slow the evaporation.  This is definitely _NOT_
what you want to use to clean your composites prior to bonding.
Straight MC flashes off in seconds (it is what used to be used as
refrigerant back in the good old days before someone discovered freon)
and leaves no residue except for whatever it may have dissolved and
didn't get carried away during the wiping process.  If you can't locate
straight MC locally I believe the factory has approved acetone as an
alternate solvent... you would be much better off using that than that
gooey paint stripper.     <Marv>    ]

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