Let me explain, we slit or our steel strip which is made out of mild steel that is hot dipped galvanized and the metal is then extruded using PVC and or polyurethane jacket. We sometimes get bubbles on the finished jacket which is why I am here. The polyurethane sometimes dips , it appears to shrink which creates a dimple. I do not know why or who's idea it was to lubricate the slitting blades with hydraulic oil but I believe it is a contaminant to our extruding process. Is there a lubricant out there that is friendly to an extruding process? Maybe a lubricant that will somehow evaporate or break down so that our extruding process is no longer affected? If you have any tips or pointers please share, thank you.