Sea fishing braid
Braid lines are made from twisting together a number of very fine strands of high density polyethylene fibres to produce a braided line, and, because the lines are twisted together, any stretch that would be inherent in a single strand of material is completely eliminated. There are two fibre types used to make fishing braids. Most European and Japanese braids are made using threads of Dyneema. American braids are made using Spectra fibres. Both fibres have similar properties as they are both extremely strong. In fact, diameter for diameter, Dyneema claims to be 5 times stronger than quality steel, whilst claims for Spectra are as much as 10 times stronger!
Fishing is only a tiny part of the market for both these materials. Both are extensively used in a variety of applications from bullet proof vests to strong industrial rope and surgical stitching applications. These fibre lines are incredibly strong for their diameters. For instance, a standard 0.06mm mono line would have a breaking strain of about 500 grams, or 1lb+. A braid of the same diameter could be 4 kilos (8.5lb+) or even more!
The earliest braids used for fishing were natural Dyneema and flat in profile. The problem with natural Dyneema, as with Spectra, is that it floats. Ideal for surface lure fisherman in the USA, but not very acceptable for feeder anglers in Europe. Over time flat braids gave way to round profiled braids and 'sinking' braids. Kevlar is a very dense material and by adding anything up to 20% Kevlar strands, a braid can be made to sink. However, Kevlar is very abrasive. It was the Kevlar in some braids which started causing problems for tip anglers who were using feeder rods with poor quality lined rings. Some braids are now using polyester to help them sink, rather than braid.