Don W wrote:
It is possible to weld plastic, but it takes some practice. I've had
good luck using a hot glue gun for sealing holes in plastic tanks. The
hot glue sticks are essentially a plastic with a low melting temperature.

The glue in a hot glue gun used for arts and crafts work won't
work...it's just the same stuff that comes in a pot with a brush, only
hardened into sticks, no better for mending polyethylene than Elmers.
You'll need polyethylene rods which may not fit in a Walmart glue gun.
You need to buy a heat welder that uses poly rods at Home Depot.

And it does indeed take some practice, because just stuffing new melted
poly into the crack won't hold if there's any stress at all trying to
push it apart again. To get a sound mend, not only the new material, but
the edges of the crack have to be melted just enough to allow them to
become a single mass. The trick--and what takes practice learn--is in
melting enough of the tank wall without melting too much. So you might
want to buy some small poly sheets that are the same wall thickness as
the tank to practice on...you might even be able to pick up some scraps
for nothing.

Peggie
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Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://www.seaworthy.com/html/get_ri...oat_odors.html