stuart noble wrote:
Dave Liquorice wrote:
On Mon, 19 May 2008 00:05:02 +0100, Alan wrote:

These people sell it: http://www.organiccatalog.com/catalog/.
12kg for 19.95 GBP, 3kg for 5.55 GBP. Just put "gypsum" in their
search box to get toit.
http://www.wickes.co.uk/invt/220058
£4.35 for 25Kg from British Gypsum.

(17p per Kg)

Beat me to it, I was going say about a fiver for a 25kg bag of
plaster. You may even be able to get it cheaper as it doesn't keep and
has fairly short shelf life when it comes to spreading it on walls.
Old plaster sets too quickly and doesn't have long enough "plastic"
stage to allow for polishing.

Not all building plasters are equal, I suspect a finish plaster rather
than bonding, base, or multi purpose would have a higher gypsum content.

Unlike plaster, I don't think gypsum sets when mixed with water. Kind of
important for this application I would have thought :-)

Only if you leave it in large lumps. Dug in it will quickly hydrate to
normal gypsum. Or you may be able to buy out of date stuff that has
already set through ingress of damp (or scrap plasterboard). You only
want the gypsum so having to break it up with a hammer or spade is not
an issue. It will look white for a while and tread in the house etc.

The stuff is best applied late in the year. I have never bothered
preferring to add loads of organic material instead.

Regards,
Martin Brown
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