Message text written by "BP - Dwell time 5 minutes."
>their spec included "iron filings" which I had never seen
before.  the owner swore by them, saying that when they rusted it expanded
the mortar a pressed it up against the bricks so the joints were tight. <

It seems to me that I ran across this approach in some military
construction and maintenance manuals back in the 60's or early 70's, and
that we were once solicited by someone selling iron filings to put them in
our formulations. I know of at least one building in West Haven where they
were added to repointing mortar.

The rusting iron was supposed to fill any voids in the mortar rendering it
waterproof.

These days it seems like a lot of restoration work involves undoing idiotic
approaches to waterproofing taken in the 60's and 70's. Or is anybody still
repointing brick buildings using duct tape and 6000 psi waterproof grout?

Mike E.