"Gregory Young" wrote in message
...
Hi all:
The bottom line, according to Firestone, there is a "decided difference"
between the 2 liners:
The MSD sheets may look similar, according to Firestone, but they are not.
In fact he said to be sure to notice that under the product identification
section, the chemical name descriptor, PondGard is listed as "cured rubber
material", with no similar reference in their roofing line MSD sheet. Why?

All rubber products have to be cured, (vulcanized), but the method of cure
may be different. Some of the rubber products are cured by microwave, some
by brine solution, some by heated form, but the heat has to be there for
some time for the molecules to chemically bond, to give the properties
desired, such as tensile strength, hardness, elongation.

2) Their roofing liner has "additional processing", which "adds certain
chemicals useful to extend the life of the material". He would not
identify
the specific agents added, except to agree with me that "some" companies
add
plant inhibiting compounds to their roofing liner.

I suspect the additional chemicals used in the roofing liner, that would not
be needed in pond liner is antioxidants. The roofing would be subject to
ozone in the atmosphere, that the pond would not be subjected to. I have
seen oils and waxes used as antioxidants, and both will migrate to the
surface of the rubber sample during ozone testing. If insufficient amounts
are present, the rubber cracks like old tires on a parked car. Whether
these would be toxic or not, I don't know.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html



.
Happy ponding,
Greg