[en] The influence of ion implantation of ⁵⁶Fe and ⁶³Cu on the bulk properties of the conduction electrons in aluminium has been investigated with the reflection conduction electron spin resonance (CESR) technique at 21 GHz. The doses were kep low and varied from 3 x 10¹³ to 5.4 x 10¹⁴ atoms cm^-2. Below 25 K, large line broadening and an unexpected g rise has been found in the nonannealed Fe implanted samples, which indicate the existence of surface spins. From the similarity between pure and ion implanted Al it is concluded that surface spins may be important in the so called pure Al too. (author)