Damage to bed surface from heat or chemical or..? The original bed surface of my Ender 3 has become brittle and finally cracked, requiring replacement. I'm trying to figure out what the cause might have been to avoid it happening again. It seems to have started after using "flex PLA", which involves both high temperatures (225&nbsp;&deg;C) and plasticizers mixed in the PLA. Could either of these have contributed to the problem? I'm not sure what material the bed surface is - it's the new one that's removable and held on by clips. If it's PEI, the glass transition temperature is supposedly 217&nbsp;&deg;C, just above what I use for normal PLA but well below what I'm using for the flex, so perhaps that's the cause?

Image of the damage:
The build surface on the Ender3 is a BuildTak clone. The picture is a bit unclear, but given my experience with BuildTak (clones) this certainly damage because of heat. You can, as suggested before, replace the bed surface, but I do not think it is necessary at this stage. 

Normally these surfaces do not get damaged that easily but to prolong the life try to keep the following points in mind:


Correct height between nozzle and bed.
Don't let the nozzle heat up/cool down close to the bed (for example after a failed first layer).
When using sharp tools to remove prints be careful nut to dig into the surface.
Don't use too high of a bed temperature (my BuildTak clone once had bubbles forming because the layers separated)
Clean/degrease the bed, although this is more to ensure proper bed adhesion.
I found out that if the bed stops sticking you can revive it by sanding it a bit.