Time capsule -- anyone ever done one?

[Ian Stirling]

One solution would be to use a 24k gold box, TIG welded together.

[John Rumm]

and use archival quality acid free paper for any that goes in there...

[Andy Dingley]

A carelessly installed lead gutter may leak in just a year or two. Properly applied leadwork is treated with "patination oil" after installation and it's this patina that provides much of the corrosion resistance. A roof itself isn't that bad, as they tend to dry fairly quickly after rain.

[Andy Dingley]

Almost all paper is acid free - when they make it. If you want it to last, then it needs to be buffered (i.e. an excess of an alkaline filler added) to ensure that it doesn't become acid in the future. It should also be made from the right sort of fibre (i.e. not lignin-rich wood fibre and not produced by an acid rich process). If you take the "pulp" paper as used for cheap paerbacks and filled it with chalk, the stuff would still be brittle and acidic a few decades hence.

"Acid free" paper labelled as such is by and large garbage and won't last a decade. If you want to trust it, then get it from a reputable maker (and that doesn't include the impressively packaged "Crimson & Blake" tat sold in the poundshop bookshops, no matter how convincing it looks). It will also be labelled as "archival" or "buffered", not just "acid free".

OTOH, avoid buffered materials if you're working with colour photographs, as they don't like alkalis any more than acids.

[Mungo "two sheds" Toadfoot]

Inside a 6' square reinforced concrete vault. With a 1000 year "Here I am" beacon inside.

Si

[Andy Dingley]

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.

[Anna Kettle]

Who are the other big two? For me they would be Tiranti and South Western Industrial Plaster but I suspect you mean different companies which maybe it would be handy for me to know about

Anna

[Andy Dingley]

Probably more paper-based / museum conservation than the sort of architectural conservation you deal with - Preservation Equipment and Conservation by Design