In article <bqEXA.133262$0S.6...@fx17.am4>,
Bonding coat plaster will do this - I've used it to hold metal back
boxes to plasterbaord for sizes where plasterboard fixing back boxes
are not available. Ideally, get the plaster to ooze through some holes
in the metalwork, but it bonds well enough that's not normally a
problem.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]