Keeping the nylon dry is of paramount importance. My Markforged machine prints only nylon (the "Onyx" material being carbon-fibre whisker reinforced nylon). The reel resides in an airtight box and each reel comes hermetically sealed, with large desiccant bags that you then place in the box with the new reel. Print nylon with too much moisture in it and you inevitably get foaming caused by steam. This causes poor control of both extrusion, dimensional accuracy and can cause adhesion issues. Anyone with experience of th eplastics industry (mine stretches for more decades than I'd care to remember) will be well-versed in which materials need pre-drying and ALL nylon types are known to be hygroscopic -- some more than others. ABS ideally would be pre-dried but if anyone is printing polycarbonate (PC) and expects its renowned toughness to be present in the printed parts will be in for a nasty surprise if too much moisture has been picked up prior to printing. The water responds not only physically, by turning to steam but also reacts chemically with the PC and causes severe embrittlement.
