The previous few posts have been primarily concerned with exploring the aesthetic potential of the recycled nylon from Cornish fishing net. I hope you agree that this was useful, and as I’ve repeatedly stated these are only explorations. Its up to the customer how they use the material. Its my job to open doors not close them.
So as production testing advances and the process is refined behind closed doors (I’m not going to tell you what I’m doing to improve the process so don’t ask), I’m shifting from look at feel and towards empirical quality in engineering terms.
For those who already 3D print in nylon there will be little news here as regards the technical challenges and a quick look at the result will inform the informed about the kind of testing that I am doing. For the unititiated there are some underlying challenges related to the material science behind nylon production, use and re-use that have to be addressed to the satisfaction of a technically motivated customer. Prime amongst these is the hygroscopic nature of nylon.
A hygroscopic material absorbs water, not like a sponge into open voids, but into its molecular structure. Not all plastics are hygroscopic and some physical forms promote the attribute where others reduce it, in general the higher the surface area to volume ratio the more sensitive the material will be. Nylon 6, the main constituent of monofilament fishing nets, is hygroscopic and has been shown to absorb up to 9.5% by weight of water. So simply allowing nets to drip dry prior to processing isn’t enough. We do need to dessicate the materials arising from them at some points in the recycling process.
Of course water isn’t just present in the sea (shocker !), its also present in the air as humidity, can be released by the materials when they are heated and is present on everyone’s hands, sweaty palms or not. So it is important to know where water is, how it interacts with the materials, how to mitigate its actions and when is best to mitigate its actions.
You could go nuclear on it and dry everything to within an inch of its life and live in a bubble. But apart from the detrimental health effects on workers, if you stuck the whole process in a zero humidity clean room, that isn’t going to be the best or most economic use of energy or capital.
Long and short of all this dull, repetative, behind the scenes work is that the Fishy Filaments recycled nylon filament made from used fishing nets with no additives and no harsh chemicals used in its processing can definitely be used to build extremely tough and resilient 3D printed forms.