Heat Bed Question

Just noticed that my heat bed is starting to change colour in patches underneath the glass? Looks worse when the bed is hot, like bubbles. Is this normal? I print mainly PLA and ABS using the built in profiles.

So the light colored areas are air bubbles or separation of the silicone heater from the bottom of the glass. The small raised bubbles you can feel are air trapped between the pei sheet on top and the glass bed. Search for it. Unfortunately it’s all to common. Live with it, get a new bed, or redo it with a thicker pei sheet

Thanks for the reply. I can live with the PEI sheet bubbles and I have a spare sheet too.

The header element separation is a concern, I imagine over time the bed won’t be a consistent temperature. Seems like air has formed between the silicon and glass…