As Robert states, Super Glue is fine. Not QUITE as William suggests,
not all superglues will deteriorate. The Zap line of products has
excellent holding power and stability. I have a ten+ year old R/C
submarine held together by the stuff that runs to 12 feet of depth...
any failures would be more-or-less permanent. So, if after 10 years it
is still good under those difficult and stressful conditions, I would
suspect better if the fix is 'at peace' during its life.
Another trick, if you cover the joint on the smooth (visible) side with
Scotch brand MAGIC TAPE (with the green plaid trademark), and burnish
the tape with a fingernail, that will protect the crack edges from
spillover. Get the crack clean and tight, cover with the tape and apply
the glue from the blind side. LET IT DRY. Even "instant setting" glue
takes time as super-glue cures by catalytic reaction, when it is not
exposed to air, it takes much longer. Remove the tape, you should have
a nearly invisible seam.
If you want to bridge the inside later with Epoxy and/or JB Weld (I
would suggest the latter if color is not an issue), that will certainly
stabilize the crack against further movement and remove stress from the
glue itself. I have found that expedient unnecessary to-date.
Peter Wieck
Wyncote, PA