Ƙunƙashin zafin jiki na fiberglass shine babban dalilin rashin kwanciyar hankali na tef na PTFE. A PTFE sintering yanayin zafi (360-400 ° C), saura danniya saƙa da aka saki. Idan ba a tsare ba, masana'anta suna raguwa; idan an kame, damuwa na ɓoye yana kulle a ciki, yana haifar da raguwa daga baya yayin maganin manne (150-200°C) da dumama amfani ta ƙarshe. Magani: yi amfani da fiberglass da aka saita pre-zafi tare da <0.5% raguwa a 400 ° C, kawar da ragowar damuwa kafin sutura.