I have a catheter process creating bubbles in the catheter walls.
The process is essentially pebax onto pebax reflow (fusing). There is a SS braid in between the pebax materials and FEP is used as the outside heatshrink.
The shaft is heated in a vertically translating hot air nozzle shrinker to above the pebax melt temperature.
Pebax in question is 55D.
I'm having trouble determining cause of the bubbles.