Observations on Nylon versus Polyester mist nets.

Polyester (nearest net) and nylon nets of equal age showing the difference in colour after 5 years use.

During my training and later as a recently qualified C-permit holder, I asked other ringers which mist nets were best and quickly realised that there was no consensus. The answers I received seemed to relate more to personal preference, ringing site, species targeted and, in some cases, brand loyalty than anything supported by facts and figures. Over recent years, as I have gradually increased my net stock, I have purchased North Ronaldsay, Ecotone polyester and Ecotone nylon nets in that order, driven partly by price and partly through experience.

I have trawled through the information available on various net retailer’s websites but again there is little consensus and some contradictions. In contrast to other sites Avinet report that “Polyester is a little bit softer but agree that it has a little less elasticity than nylon and performs better in wet and humid climates. Nylon can be just as durable as polyester, but performs better in maintaining tension in dry, well-aerated sites.”

https://www.avinet.com/pages/mist-nets

NHBS state that “polyester fibre is UV resistant and does not absorb moisture.  In the morning or after rain, just shake the net to remove droplets.  Polyester is also stronger and more durable than nylon. The NHBS blog states that “nylon nets are deep black, UV stable and softer than polyester.”

https://blog.nhbs.com/how-to-guides/guide-to-mist-nets/

Robert J. Arndt and Brian A. Schaetz, writing in Bat Research News state that “Although nylon thread is slightly stronger than polyester, polyester is more resistant to shrinking and stretching.”

https://www.researchgate.net/publication/306079598_A_Tale_of_Two_Deniers_Nylon_versus_Polyester_Mist_Nets

P. Busse and W. Meissner in the Bird Ringing Station Manual state that “The most UV sensitive are nylon nets. . . . . Nylon netting is much softer than polyester.”

So, what are the facts and do the differences matter?

Thread manufactures state that nylon is one of the strongest synthetic threads in use today. It has a higher strength-to-size ratio in comparison to polyester thread and is also known for its flexibility and stretch. . . . Nylon does not have the UV resistance of polyester thread and will not last as long outside. Polyester is known for its strength, durability, and low shrinkage and stretch. It’s the most common thread for outdoor applications. Compared to nylon thread, polyester thread has superior resistance to UV rays and moisture, but much of its strength is lost after prolonged exposure to sunlight.

In practice, I have found no significant difference in the performance, durability or catching ability of either material. All my 18m nets have been exposed to the same conditions for the same length of time and all the net rides have the same orientation in relation to the sun. I keep a log of my net repairs and the polyester nets have needed an average of 40 repairs a year compared with 32 for the nylon nets. This may sound like a lot of snapped threads but, with over 250,000 meshes in an 18m net, it’s really only a handful of small holes. The lower number of repairs to the nylon nets agrees with its higher strength-to-size ratio.

The other area where the nylon nets have significantly outperformed polyester is in colour durability. The recent demise of one of my polyester nets, after being “bombed” by a badger, has meant mixing the two materials in the same net rides until a replacement arrives. The nylon nets are significantly darker and blacker, whist the polyester ones have faded to a mid-brown. However, this does not seem to have affected the catching performance. Ultimately, with little difference in price, it’s a matter of personal preference. I’ll be sticking with nylon from now on!

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