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Re: Saran Wrap as a Dielectric

Tesla list wrote:
> Original poster: "David Huffman" <huffman-at-fnal.gov>
> What ever happened to truth in labeling? I thought I remembered seeing
> polyethylene on the label. Bert, where did you find out different? Just
> curious.
> Dave


Well, if the package actually states that it's polyethylene, then I'd
believe it. However, the Dow Saran brand wrap I have in my kitchen
simply states that it's plastic film. Dow makes many different types of
branded Saran wrap, and owns the trade name. Dow Saran is all
polyvinylede chloride (PVDC) film - this material has excellent gas
barrier properties, and is extensively used for food preservation. If
your plastic is not specifically identified on the box, it should be
possible to identify it by carefully using the "burn and smell" test on
a small piece. 

True LDPE burns with a blue flame with yellow tip, will drip when
burning, and will have a distinct paraffin odor. It also floats in
water. There's no other plastic that has all of these properties! PVDC
is about 1.7X as dense as water, and has an acrid odor when burned

BTW, a handy plastics identification chart can be found at the Port
Plastics site:

When I was trying to identify the makeup of Saran Wrap a couple of years
ago, I simply looked it up on the web using a search engine. Doing this
yesterday using Google resulted in some interesting reading. It turns
out that Saran film was accidently discovered by a Dow Chemical
scientist back in 1933. Today's Saran Wrap is actually a plastic alloy
consisting of about 87% vinyledene chloride and 13% vinyl chloride.
Check out:

The source I most often use to provide information on materials
(including Saran film and LOTS of other stuff!) is Mat Web:

On the above site, select PVDC under the Thermoplastics section, and
you'll find 11 different grades of Saran film made by Dow, 10 grades of
PVDC-coated polyester films made by Dupont, and overviews of both


-- Bert --
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-com
Web Site: http://www.teslamania-dot-com