Fellow Listers,
To the best of my knowledge, the fogging we observe on
our MG windshields is due to the slow "evaporation" of plastisizer
from our plastic dashboards. The function of a plastisizer is to
make the plastic flexible...for example, PVC (poly(vinyl chloride) is
fairly brittle, but the addition of a carboxylic acid ester softens
it up a bit, making it a suitable material for garden hoses, plastic
covers, and so forth. Carboxylic acid esters are organic compounds
which are derivatives of carboxylic acids, which have a variety of
uses from flavorings and solvents, to plastisizers. In addition,
other compounds are used as plastisizers, but we've come to the end
of my knowledge base here.
Typically, for the plastic in our dashboards, a non-volatile
plastisizer should be used, however given the fact that our cars are
typically exposed to sunlight (and therefore high interior temperatures),
over time this supposed non-volatile plastisizer can "evaporate"
...thus leeching out and forming on the windshield. From here,
I imagine it can become baked on and would therefore be
somewhat difficult to remove.
As far as removal goes, I heard somewhere that a
concentrated solution of ammonia does the trick...but I have not
experimented with this myself and therefore don't know if it works.
If anyone chooses to try this, I would remind them that even though
supermarket-grade ammonia is only about a 5% solution, it will
produce strong vapors, and these vapors are exceedingly irritating.
Adequate ventilation and suitable skin protechion (read, gloves)
would therefore be required.
If anyone tries this, let me know if it works!! I have
some "fog" I'd like to get rid of!!
Best Regards,
Matt Milkevitch
Matthew Milkevitch
Graduate Student, Ph.D. Candidate
Dr. Karen J. Brewer(Chem), Advisor
Dr. Brenda W. Shirley(Biol), Co-Advisor
Va. Tech
Blacksburg, VA 24061
(540) 231-4708
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