When I removed an air filter recently I noticed it had this a glue like substance going across it as you can see in the picture. It must have either come like that or the mechanic put it on.

Just wondering what is the reason for putting this on? Is this an anomaly or do lots of air filters come like this? enter image description here

1 Answer 1


Many air filters come like that. It's a line of glue, used to keep the pleats in the filter at the correct spacing. Not needed on smaller air filters.

  • That's structural glue.
    – fectin
    Commented Aug 15, 2022 at 16:06

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