AW: superglue

[d h webber <d.h.webber@xxxxxxxxxxxx>]

Hello

Superglue is often excellent for preventing movement in cracks, and not
just in stone.  I used it years ago on a crack in a porcelain sink, the
crack kept getting longer until I had the idea of applying liquid
superglue; since the treatment it has not moved at all.

Two interesting points regarding superglue and other cyanoacrylate
adhesives:

1]  The curing process for cyanacrylates is initiated by water, and most
effectively by water which is alkaline.  Acidic surfaces, even when
damp, will inhibit curing.  Thus cyanacrylates are poor adhesives for
wood, which is more or less acidic depending on the variety; some types
of wood are impossible to glue with these adhesives.  Stone sufaces are
normally alkaline, particularly for sedimentary rocks which usually
contain carbonates, and will be bonded rapidly (except for polished
impervious stone surfaces in extremely dry conditions).

2]  As far as I am aware, cyanoacrylate adhesives rarely, if ever,
contain UV stabilisers or UV absorbing pigments.  Thus, the hardened
adhesive will be degraded by sunlight, but in a narrow crack in a dark
(or at least UV absorbing) stone then little light will penetrate far
into the crack (unless the crack has direct sunlight shining parallel
into it).  Thus, the adhesive should last for many years.