superglue

[Don Dougan <dondougan@xxxxxxxx>]

Clive;

In my reply to Andrei I didn't mean to imply that "Super Glue" was a
panacea -- I also use Tenax or Akemi for major repairs.  But that was not
the case here -- Andrei seemed to be trying to keep the stone from
fracturing further during the working process.  It did not sound to me
that  he would be trying to 'repair' a piece that has broken or has major
structural flaws - just ones that made the working difficult.

Let me also point out that any jointing or repair job that requires a
FILLER adhesive also requires a mechanical structure such as a metal pin
for integrity -- in my own work I do not trust even an epoxy's bonding
power when a section of stone is liable to chemical failure due to
unforeseen climatic, environmental, or temperature variations.
Most Tenax and Akemi fillers are polyester-based and as such are ideal
for color-matched fills, but they are also very brittle and the
manufacturers do not recommend the polyester versions for repairs for
outdoor use.  Epoxies are much stronger, but the color and the structural
integrity of epoxies also degrades with UV exposure.   For my own
peace-of-mind I always drill and pin to provide mechanical structure
(stainless, brass, or aluminum pins depending on the strength
requirements of the particular situation) in addition to any adhesive if
the joint or repair is actually combining two or more pieces.  That way
even if the adhesive fails, there is back-up structure to prevent
catastrophe.

I do however think that the situation as described by Andrei called for a
solution to strengthen a weak or flawed area of what is otherwise a whole
and unbroken work.  To me, that is more akin to cosmetic work rather than
structural work, though not having seen it I admit I could certainly be
wrong.  The Super Glue solution provides the strength and penetration
into the relatively shallow fissure and thus keeps the spalling of the
relatively weak edges of the crack during the working process.  Simple
problem, simple solution.

You are correct in implying that the Super Glue alone does not provide
enough structural strength if there is a serious problem.  It could be
likened to using spackling to fill a crack in the wall - if the crack is
in a non-loadbearing wall and would seem to be simply due to the settling
of the building it will be easy, commonsense solution  -  as opposed to
rebuilding the wall!  However, if the crack is in a loadbearing wall that
is cantilevered over the edge of the canyon, then spackling would simply
be the solution of a careless fool.

Each problem requires a thoughtful and observant solution tailored to the
needs of the particular design -- no one approach is ever the only one,
or the right one in all situations.  That is why my studio shelf is
stocked with supplies purchased from the industry supply houses as well
as the local hardware store  -  and even the grocery store!  Sometimes
the solution warrants the use of $400 per gallon materials, while at
other times the $14 solution is the common sense one - and one should not
be afraid to use whichever one will suit the situation best.
(and I DO try to avoid building over canyon walls . . . )