The warnings below only apply to the PTFE if it is in the melt zone (aka the heater block). If our ToughTubing or other higher-end tubings are just being used for their tighter tolerances in an all-metal hotend setup then you do not need to worry about the PTFE off-gassing as it is not exposed to the nozzle temperatures.
PTFE is a polymer that has a high heat resistance and low friction which makes it a great material for bowden tubing applications. However, when used in the melt zone of your hotend you need to be aware that temperatures up to 250C are generally considered safe. However, past this, the PTFE can emit what is referred to as off-gassing. This is not typically harmful to humans but small animals, especially birds can have their respiratory systems harmed. We recommend staying under 275C as higher than that has been tested by us but can reduce the life span of the tubing in the melt zone and cause more off-gassing. If you want to regularly print over 275C we recommend going with an all-metal hotend. According to other publications, PTFE will start off-gassing around 300C and higher.
You can use the Tough Tube and other high temp brands in the melt zone but make sure you take the proper precautions. Many machines on the market come with low-quality PTFE already in the melt zone and they will emit gasses as they are heated. There is nothing wrong with using our tubing or others in the melt zone as long as you take the proper precautions to minimize the off-gassing. In addition to that, the material you print with may also be off-gas as it is printed.
