Expected heated bed wear and tear?

Lately I’ve been getting air bubbles on the heated bed; they have been slowly getting larger. The air bubbles don’t seem to affect the print quality or bed adhesion. However I’ve had a failed prints where the “max temp” of the bed was reached, it was then i noticed the temperature readings are spiking.

I’m printing with HIPS with the bed temp at 110degrees, I’ve turned down to 100degrees to perhaps prevent the spikes reaching 150degrees.

Any ideas what could be causing this?

At what point is it expected to replace the PEI coating? The printer sees moderate use; I print prototypes for work.


Any assistance is greatly appreciated.

stop printing at 110 for the bed, use a max of 90.

I have 1500-2000 hours on my taz 5 original PEI and it is still holding strong. I have 2 small bubbles from a misfortunate print with nylon, but it still prints fine even in those areas.

The Yellow discoloration on your bed looks like the Heat pad is/has started to detach from the glass. The adhesive turns yellow when it has dried out. so you may have issues with maintaining the temp of the bed soon.