Capricorn
Capricorn lists melting temps, not degradation temps when advertising their PTFE tubing.
Capricorn tubes have a unique selling point in that their quality control ensures accurate inner and outer diameters of extrusion. This is in contrast to generic manufacturers who may not have as stringent a requirement for manufacturing.
A 1.9mm ID (inner diameter) has been shown to help in reducing hysteresis when extruding flexible filaments in a Bowden setup but in other setups, i.e. filament with a higher variance in diameter, this can actually become detrimental. Use best judgement when deciding what form or brand of PTFE to use in your printer.
Capricorn tubing is relatively high quality for its price point, but there is insufficient independent evidence to show that it has more thermal resistance to pyrolysis than "generic" PTFE tubing. One difficulty in testing is that due to the colorants in the PTFE resin, the distinctive "browning" of degradation or pyrolysis is much harder to detect. Another point of concern is to do with Capricorn's line of translucent "TL" PTFE. Though the exact composition of their resin remains proprietary, the nature of PTFE and related fluoropolymers speculatively suggests the addition of PFA or FEP (which are optically transparent) into the mix. The issue with this is that both PFA and FEP have lower working temperatures than PTFE. PFA is rated to a similar ceiling of 260 C but has a higher thermal conductivity whereas FEP undergoes degradation at temperatures as low as 200 C. Unfortunately without further evidence, this must remain speculative.
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