The black sheetrock screws DO rust, though they won't if you completely
encapsulate them (that would mean from all sides). If you're concerned,
you can use galvanized or stainless decking screws.

peter wrote:

Has anyone ever used drywall screws (the black ones for screwing
plasterboard - I think you call it sheetrock in the US- onto metal
studs and plastering over) for holding the strips in the right
alignment, instead of wooden dowels and/or plywood cleats, or is it a
really dumb idea? I mean just for those annoying bits where the new
strip won't quite line up over the one in place.

The screws don't rust as far as I know and as the whole lot is
encapsulated in epoxy afterwards I doubt if they ever would. I've used
them for fixing things into wood for years and never noticed any
detrimental effect, so I doubt that they would cause an damage to the
wood, assuming a pilot hole was drilled first.

It's just that they are so cheap and are so easy and quick to screw
in.

Another Pete

Brian Nystrom wrote in message ...
The black sheetrock screws DO rust, though they won't if you completely
encapsulate them (that would mean from all sides).

Oh yes they will (proved it a few times).

If you're concerned,
you can use galvanized or stainless decking screws.

There is a bugle-head screw (same profile as a drywall screw) used for
cement backer board, commonly called by the brand name Durock in
America, which is structurally approved as corrosion resistant &
commonly installed over steel studs in landlubber construction, using
a SS eschutcheon (for Durock), and sometimes for light curtainwall
construction. It isn't galvanized and I don't think it's SS (not
close at hand to double-check either). It has stood up well in a
light marine environment for me, as well as the demands of
(hygroscopic) backer board often used in wet/corrosive locations like
ceilings over chlorinated swimming pools, tiled chemical treatment
rooms, etc. I no longer have the designation at hand, and local
tradesmen simply call them "Durock screws." They may only be
cadmium-plated (a guess). There are a variety of "sheetrock-like"
fasteners unknown to consumer markets, if you find them temptingly
easy to use - suggest check with a commercial drywall supplier or a
wholesale fastener house. Some have superior drive heads, too,
instead of that horrid Phillips affair that is so easy to booger.