An aerosol generating device comprising a storage portion 113 for storing an aerosol-forming substrate 115, a vaporizer 119 for heating the aerosol-forming substrate 115, a capillary material 117 for conveying the aerosol-forming substrate 115 from the storage portion 113 towards the vaporizer 119 by capillary action, and a porous material 201 between the capillary material 117 and the vaporizer 119