The polysemy of deverbal event nouns-nominalisations-is frequently discussed in the literature. However, one interpretation associated with nominalising suffixes has never been evoked-the instrument interpretation. This paper is dedicated to the rare instrument interpretation of-age nouns (henceforth N-age): allumage 'ignition', attelage 'harness', bandage 'bandage', embrayage 'clutch', garnissage 'garnish', gommage 'scrub', maquillage 'makeup'. We present the results of a study of instrumental N-age nominals, based on a sample of the deverbal-age nouns collected from the TLFi. We outline the semantic conditions that determine the presence of the instrument interpretation for these nouns and argue that this interpretation is not based on semantic drift from the corresponding eventive N-age; rather, it results from the specific properties of the morphological rule (i.e., its possible output(s)) and from the semantic properties of the input verb. This analysis leads us to reconsider the polysemy of deverbal nouns, not as systematically based on the notion of semantic drift from a derived lexeme, but, for some interpretations, as a construct of morphological rules, given specific semantic constraints. We conclude with a formalisation of the semantic sub-pattern within the N-age rule which generates the instrumental nominal. For the semantic representation of the base verb, we follow the theoretical framework of Levin and Rappaport (1995 and later). We incorporate this semantic formalisation in the wider representation of morphological rules envisaged in lexematic morphology.