resin formulation is external grade, weatherable compound prior to any purchase. Once
determined, the material is purchased in bulk and shipped to our plant in Alabama. Once in
house, visual inspection of the scrap takes place, relying on our 51 years of experience to verify
quality. We then separate the scrap by color, if any, and begin a regrind operation to reduce the
scraps to a pellet measuring between 1/4 in. to 3/8 in. particle, which insures a smooth conversion
in the extruder. We send the ground resins through a metal detector and separator to insure no
foreign materials are present. The resins are fed into a hopper that smoothly feeds the extruder
barrel. This barrel contains heating elements that convert the pellets into a molten, flowable vinyl
that is extruded through a mono-extrusion die positioned at the other end.
Using a mono-extrusion process insures that the resins are bonded at identical temperatures
throughout the cross section, precluding any possibility of delamination problems. Northstar
chooses to mono-extruded through a die (see below) to create a high performance monolithic
piece. Unlike "co-extruded" parts which consist of an inexpensive substrate laminated with a
"paper" thin layer of weatherable capstock material, mono-extruded pieces do not delaminate and
function as one unit as demonstrated by flexural, tensile, and creep testing. Mono-extrusion has
withstood the test of time; the oldest vinyl seawalls that are in existence are ones that were mono-
Mono-extrusion die / calibrator.
The molten PVC material exits the die as a formed piece, which then goes through a series of
"sizers" that bring the product into proper tolerance as it goes through cooling baths in order to
set the final shape. As the product exits the baths, it is cut into specific lengths by an automatic
circular saw, palletized, banded and prepared for shipment.
The only additives added to this process would be small amounts of colored virgin resin in
order to obtain a consistent color balance.
The addition of a small amount of virgin resin has no effect whatsoever on the physical or
chemical properties of the finished products.
5. Testing of products
Our final product testing begins with constant visual inspection and random caliper
measurements to insure that the product is within acceptable physical dimensions according to