Laboratoire de Tribologie et Dynamique des Systèmes, 36 ave. Guy de Collongue, F-69131 Ecully Cedex. The hollow glass forming process requires a periodic lubrication of the metallic parts in contact with glass. This lubrication induces many process defects, so that many studies have been undertaken in order to reduce or completely suppress the lubrication. A tool called loading sensor allows the in vivo investigation (directly on the forming machine) of the dynamic contact between a viscous glass and a metal, representative of the loading step of the gob inside the blank mould. This paper is dedicated to the study of the influence of the surface morphology upon the friction of the two materials. We clearly identify some major morphology parameters governing the friction phenomenon, and thus, give industrial recommendations for machining optimised surfaces.