Dave wrote:
On Sun, 14 Jan 2007 15:39:48 -0500, Jeff said:

You have to tell us whether you mean Polyester, of which Dacron is a
brand name, and is used for all sorts of running rigging, or
Polypropylene which is a much weaker rope, but which floats and is
used for water toys, etc. There is a huge difference in their ability
to hold knots.

Seems to me it's fair to assume he's asking about polypropylene, since
there'd be no reason to ask about polyester lines. In fact I see no reason
to even ask your question other than to demonstrate your knowledge of
chemistry.

Sorry, I had actually composed a response assuming polyprop and then
realized the ambiguity. Part of the problem, however, is that
nowadays the newer forms of polypropylene will hold a know rather
well, so to answer the question, one must know what type it is, and
what the application is.

For holding down a tarp, I'd throw away the presumably cheap, slippery
polyprop and go to the Home Depot where you can buy a lot of line that
will hold knot and is cheap enough to just chop away in the Spring.