You wouldn't think there would be much to making a winter
pool cover - buy some fabric, sew it and sell it. But producing a winter cover
isn't really that simple. There are substantial differences in the woven fabric
used to make winter pool covers. The following commentary will try to provide
some helpful information on winter covers.
The woven polyethylene fabric used to make winter covers has three main
parameters: weave, denier, and coating.
This refers to the density or number of individual plastic strands that comprise
the fabric. Web refers to the number of strands per inch longitudinally. Weft
refers to the number of strands attitudinally. Normally this is expressed as a
material having a 12 x 11 weave or scrim - the material has 12 strands per inch
up and down and 11 strands per inch across. The denser the weave the longer it
takes to make and the more costly and stronger it is. Other parameters being
equal, a 12 x 11 scrim is stronger than a 9 x 7 scrim.
This measures the thickness of the individual strands comprising the weave. The
higher the denier number the thicker and stronger the strand. Typically, the
denier used in winter fabric is anywhere from 400 to 1200.
The coating is a thin layer of pigmented plastic applied to both sides of the
finished scrim to make it water proof. It is measured in mils and can be
anywhere for 1/2 to 3 mils thick.
- ULTRA VIOLET RESISTANCE
The chief enemy of any plastic is the ultra violet rays of the sun. Unprotected
plastic is quickly degraded and can be made brittle unless carbon black is added
to the resin to block UV radiation. In pool cover material the individual
plastic strands, as well as the synthetic thread used to sew the covers, should
be black indicating that they are resistant to ultra violet light.
- WHAT DOES ALL THIS MEAN TO YOU?
The above factors determine the strength and durability of the winter pool
covers you buy. The manner in which they are produced will directly effect how
long your cover will last. Most importantly, this would suggest that winter
covers produced from domestic versus imported materials are of better quality.