Hot sand is also frequently used for bending plastic.
Practical sailor had an article on PVC:
"Measure enough playground sand to fill your pipe, and then add an additional cup to compensate for any spillage. Heat the sand to 450°F in an oven. (You an also cook it on a stovetop or grill.) Use a stainless-steel pan. Stir and monitor the temperature with an infrared thermometer. Pour the hot sand into the pipe with a funnel. Close pipe top with duct tape. Although 450°F is above the recommended bending temperature, the conductivity of sand is low and it will not cause the plastic to overheat.
Wait about 2 minutes for the outside of the pipe to reach 200°F and for the pipe to get a little floppy. Bend to a radius of not less than 5 pipe diameters. Cool by running water over the pipe, wiping with a wet cloth, or leaving in a bending jig for 30 minutes or more. Pour out the sand for reuse. Because the sand is incompressible and the ends are sealed, kinking is not a serious problem."
www.practical-sailor.com
Practical sailor had an article on PVC:
"Measure enough playground sand to fill your pipe, and then add an additional cup to compensate for any spillage. Heat the sand to 450°F in an oven. (You an also cook it on a stovetop or grill.) Use a stainless-steel pan. Stir and monitor the temperature with an infrared thermometer. Pour the hot sand into the pipe with a funnel. Close pipe top with duct tape. Although 450°F is above the recommended bending temperature, the conductivity of sand is low and it will not cause the plastic to overheat.
Wait about 2 minutes for the outside of the pipe to reach 200°F and for the pipe to get a little floppy. Bend to a radius of not less than 5 pipe diameters. Cool by running water over the pipe, wiping with a wet cloth, or leaving in a bending jig for 30 minutes or more. Pour out the sand for reuse. Because the sand is incompressible and the ends are sealed, kinking is not a serious problem."
Using Heat to Bend PVC Pipe - Practical Sailor
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