Most of our netting is made from high density polyethylene monofilament which is black and contains ultra-violet stabilisation additives to a level of 2% which gives a protection of 400kLy. The intensity of UV radiation is measured in kLy (kilo-Langley), a unit of which represents how much UV radiation energy falls on a cm2 per year. In the UK this figure is about 70kLy compared to 220kLy in the Sahara.
Polyethylene has a temperature range from -100C to +115C. It is chemically inert and does not rot or absorb water.
There are various methods used to manufacture nets. We stock three general types of net:
This is the traditional way of making net. The process starts with making the twine. This can be a monofilament but is more usually a multifilament i.e. a number of strands are twisted together. The degree of twist and direction of twist are important factors. We use a Z twist (anticlockwise). The thickness of each filament is specified in Denier (as for tights). We use 600, 800 and 1000 denier filaments and the twines are either 2, 5, 6 or 15 ply.
The twine is wound on to 300 or 400 spools on the net making machine. The net is made by knotting the twine from adjacent spools one row at a time i.e. 300 or 400 knots per row. The knot we use is called a single English knot. The net is complete when the spools run out or for longer nets new spools are added and the twine joined. As it comes off the machine the net has diamond shaped meshes. However this is generally not useful so the net has to be “squared”. This involves joining one long edge of the net to the opposite long edge to make a cylinder. The twine and knot used are the same so this join is invisible. This can only be done by hand. The net is then cut diagonally in a spiral round the tube of net then when the net is laid out flat it can be pulled in to a square shape.
Woven or knitted
This is a cheaper way of making a net because it is faster and requires no work by hand. The technical term for this type of net is Raschel which is a type of warp knitting in which parallel monofilaments are looped together in a zigzig pattern along the length of the net. Our Woven net is made from two strands of 500 denier filament looped together which is then interlooped at the mesh corners. The net produced is a diamond mesh. It can not be “squared” so the net can stretch i.e. as opposite corners of the diamond are stretched widthways, the other corners will shrink lengthways. Windbreak is also a Raschel net but has the addition of crossways or weft strands. Our insect net is a standard weave with the weft monofilaments crossing the warp monofilaments at right angles.
This is a two stage process. The polymer is melted and forced through nozzles and cross strands then set at the joints as the material cools. The net is then reheated and stretched both length ways and widthways (Biorientation) to make a lighter weight net. This type of net is much more rigid than other types of net i.e. the meshes do not deform very easily.