Jahn products

Can anyone tell me anything about Jahn products. Specifically,
what's in them (stone patching and re-pointing compounds).

I am surveying a number of statues and monuments one of which, a
fountain, has been recently "restored". It is a mess right now. The
fill material (supposedly Jahn material) is cracked, it also looks
terrible next to the original material (a porous limestone). There
are also several rather large patches of salt efflorescence along
some of the mortar joins.

I have been to the cathedral stone web site, but they don't give any
real info.

Also, any feelings on the appropriateness of these products for use
as conservation materials? The instructions for the stone patching
compound specifically state that 1/2" of sound stone should be
removed from fill area etc and basically undercut the surface...
Does this mean that the patch is relying on a mechanical "locking
in" process to keep it in place? I haven't removed the fills from
the fountain but if they have undercut a fragile and exfoliating
surface....

Elizabeth Goins
Laboratory for the Analysis of Cultural Materials
University of Delaware

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                  Conservation DistList Instance 13:28
                 Distributed: Tuesday, November 2, 1999
                       Message Id: cdl-13-28-016
                                  ***