Net (device)

A net, in its primary meaning, comprises fibers knotted and twisted into a grid-like structure which blocks the passage of large items, while letting small items and fluids pass. It requires less material than something sheet-like, and provides a degree of transparency, as well as flexibility and lightness.

A fragment of neolithic fishing net.

The oldest nets found are from the Mesolithic era, but nets may have existed in the Upper paleolithic era.[1] Nets are typically made of perishable materials and leave little archeological record. Some nets are preserved in ice or bogs, and there are also clay impressions of nets.

One method of making nets is by tying sheet bends using a netting needle and a gauge. Key: *a) head rope *f) loop of the sheet bend being tied *n) netting shuttle *s) gauge *z) tongue of the netting shuttle (makes it easier to load the twine so that it does not twist as it is used)

Mending a net; binding a length of net to a new head rope. Note that, unusually, the gauge of the row being worked is larger than the gauge of the rest of the net.

Some nets are still made by hand. This 2013 image shows a Syrian refugee in Lebanon in her home, manually knotting a fishing net intended for sale.[2]

Originally, all nets were made by hand. Construction begins from a single point for round nets such as purse nets, net bags, or hair nets, but square nets are usually started from a headrope.[3] A line is tied to the headrope at regular intervals, forming a series of loops. This can be done using slipped overhand knots or other knots, such as clove hitches. Subsequent rows are then worked using sheet bends, as shown in the diagram, or another knot. Some nets, such as hammocks, may be looped rather than knotted.

To avoid hauling a long length of loose twine through each knot, the twine is wound onto a netting shuttle or netting needle. This must be done correctly to prevent it twisting as it is used,[3] but makes net production much faster. A gauge – often a smooth stick – is used to keep the loops the same size and the mesh even. The first and last rows are generally made using a half-size gauge, so that the edges of the net will be smooth. There are also knot-free nets.

Some nets are still shaped by their end users,[4] although nets are now often knotted by machine.

When a hole is ripped in a net, there are fewer holes in it than before the net was ripped. However, the stress concentration at the edges of the hole often causes it to tear further, making timely repairs important. Mending nets by hand is still an important skill for those who work with them.

Nets may be made using almost any sort of fiber. Traditional net materials varied with what was locally available; early European fishing nets were often made of linen, for instance. Longer-lasting synthetics are now fairly universal. Nylon monofilament nets are transparent, and are therefore often used for fishing and trapping.

Finishing a Mayan hammock, which is twisted rather than knotted.

The twisted net of a Mayan hammock is very stretchy, letting it hold this sleeping baby securely.

Nets, like fabric, stretch less along their constituent strands (the "bars" between knots) than diagonally across the gaps in the mesh. They are, so to speak, made on the bias. The choice of material used also affects the structural properties of the net. Nets are designed and constructed for their specific purpose by modifying the parameters of the weave and the material used. Safety nets, for example, must decelerate the person hitting them gradually, usually by having a concave-upwards stress–strain curve, where the amount of force required to stretch the net increases the further the net is stretched.

Net (textile)