Repairing PEI Blisters


I have a couple of rather large blisters under my PEI sheet :frowning:

I was planning on puncturing them tonight with a small hyperdemic needle to release the air. I have seen reports that the hole you puncture will heal after a few prints and the blisters will re-appear. I was thinking of using the need to inject something under there to remove the space for the air after all it is the air expanding that causes the bubbles.

I am thinking thermal paste as it doesn’t expand much with heat, so if partially fill the blister when hot, when it contracts it will squeeze out the extra paste leaving it flat. My other option was super glue, but that seems like a pain in the ass.


Scrub the PEI sheet down with Acetone, then heat the bed to 110 if it will go that high and leave it for10-15 minutes - then let it cool normally. The blisters should settle down.

I don’t recommend puncturing the surface…


Tried the heat cycling, and got all but three of the blisters. Remaining three are the biggest tho, and impact the print area the most. I punctured them last night (with a .3mm drill bit, can’t even feel the hole), but that seems to only partially worked, they still inflate above 80 degrees.

I think as per my original suggestion I think I need to inject something under there. I was thinking thermal paste, but now thinking maybe something more adhesive?


wouldn’t anything you put under the bubble just mean it will never be flat. I would try heat cycling it at high temp quite a few times.

From using Buildtac and having joints I cut a 250 x 250 sheet and join it to make 200x300. The join gaps after a while, so it does shrink over time… which is just heat cycles… not quite the same stuff but might work.


@ant0ny that is why I was leaning towards thermal paste, as it doesn’t expand (much) when heated. So I could fill up the bubble, use a straight edge to flatten it and the excess will squeeze out the opening. Problem is because it doesn’t really set, it could ooze out whenever pressure is applied

I am away with work for the rest of the week, but I will try to knock up some heat cycling gcode to run tonight. Even with octoprint I don’t think I’m comfortable heat cycling while I’m not home.


Thermal past might just be too much of a issue also with it on the build plate might give you places where it you have no adhesion. I wonder if you have a spare off cut if you cut a square out and inserted a piece with M3 tape.


Sadly no offcut.

I would use some sort of heat resistant epoxy, but I do want to remove it eventually. Maybe superglue? at least it will dissolve in acetone.


So I think my best bet is to re-do the surface!

I am tossing up between .003" and .004" (0.8mm and 1.017mm) I am thinking the latter would be good for flatness, but the price difference is beyond comprehension!



Doh, I was comparing .003 vs .040, the latter being what I want!