I posted this query to preservation-l a while back and got some good
response. I thought I'd toss it out to the BP wolves also to gnaw on a bit.
I appreciate any comments.

I'm currently consulting with a circa 1924 gothic revival church that has
been abandoned for over 20 years. The roof leaked for some time along the
gable end parapets (flashing and cement coping failure) and subsequently
damaged the interior plaster. The walls are interlocking hollow clay tile
with a brick veneer and plaster directly on the tile. Random testing
suggests that most of the plaster is sound and could be preserved. The
original finish on the plaster was a calcimine which was later painted over
with multiple coats of oil paint. Of course the oil paint can be brushed off
with a feather and will be easy to remove.

I am planning to have the paint removed, the calcimine scrubbed down, and
the rotted plaster chisled out. The remaining plaster will be repaired,
leveled out and repainted. My question is: what would be a good finish
coating on the plaster? I do not want any coating that would block moisture
or water vapor. My feeling is that without any membrane in the wall and high
exposure, I would like the wall system to breathe. There will be some
repointing of the brickwork, but overall the mortar is in pretty good shape
except up near the parapet. Would a BMC be appropriate? Or is there a
specific product for this type of application? Someone suggested using
calcimine again, but I worry about long term maintanence, especially if some
future building committee decides to repaint the interior - unknowingly with
latex.

Would it be worth considering consolidation of the surface to prevent any
future problem with the remaining calcimine? I've used Kyanoil for this in
the past with good results. Would any consolidant defeat the purpose of the
breathable coating by sealing the plaster too much? What would be a good
consolidant to use?

John Horton

"Sometimes I feel like I've been tied to the wippen post."