On Sat, 15 Oct 2005 19:24:01 +0100, Anna Kettle
wrote:

Conservation Resources sell stainless steel time capsules with silica
gel sachets and shreddies (their word not mine) which can be sealed and
purged with inert gas. I spex thats the bees knees of time capsules.
Should be at 245 pounds for the smallest size

I don't know "Conservation Resources" (I use the other big two) but the
expensive steel time capsules I've seen were most unimpressive in
manufacture.

Personally I used vacuum system plumbing, from my favourite scrapyard.
1/4" thick stainless, of the right grade, and properly welded. The
bolted flanges seal with wire gaskets. Most importantly (why I don't
like the commercial time capsules I've seen) the flanges were stiff
enough so that tree-root movement wasn't enough to bend the flange and
open up the skinny seal gasket.

Mil-surplus shell cases are good too. Tank shells are shipped in lovely
cylindrical plastic cases with good bayonet-fit ends and big rubbber
o-ring seals. Their lifetime ought to be good and I know divers who've
used them to some fair depth and had them stay watertight.


Web searching for "geocaching" will give you more ideas.