Help with Porcelain Bubbling Problems?

If you are using base metal alloys frequently, you may want to look at using some type of furnace purging material. It will help to remove many contaminants that attach themselves to the muffle and thermocouple. You would want to do this weekly if using predominantly base metal alloy. It is always best to follow the manufacturers recommendation for surface treatment of the alloys, although, all of these recommendations are great.