A non-drip, preferably self-adhesive, silicone elastomer composition
crosslinkable by polyaddition, such as those polyorganosilanes (POS)
bearing C.sub.2.dbd.C.sub.6.ident.Si-alkenyl units and .ident.Si--H units
but excluding fluorinated POS. The composition includes at least a
thixotropic additive containing at least a fluorinated resin, preferably
based on polyfluoroethylene (PTFE). The composition may be prepared from
a Si--Vi polydimethylsiloxane (PDMS) and a Si--H PDMS crosslinked by
platinum catalysis. Polytetrafluorethylene, a filler, particularly one
containing silicone, optionally a ternary adherence promoter such as
vinyltrimethosilane/glycidoxypropyltrimethoxysilane/butyl orthotitanate,
and other typical additives may be added to the composition. The
composition (not excluding the fluorinated POS as a possible constituent
in the composition) may be used to produce joints in situ and/or as an
adhesive, particularly in upholstery.