UKC

Any suggestions for repairing cracks in a slate hearth? All the slate repair glue options I've seen don't appear to be heart proof.

In reply to iksander:

Could you take it out and wire the reverse of the crack to hold it together so that any epoxy or similar would just be a cosmetic filler.
you could try this:-
http://www.amazon.co.uk/J-B-High-Heat-Epoxy-Putty/dp/B007PP26RI

In reply to iksander:

Has the slate cracked because of thermal expansion or because somebody trod on it or dropped something on it?

There's not much point in repairing it if the cracks are going to re-occur.

In reply to iksander:

A hearth under a woodburner or an open fire?

Under a woodburner in a non-structural joint I suspect most commonly available glues would suffice. Gelled cyanoacrylate would probably be the easiest option. Tape the top surface to prevent the fumes causing a white bloom and scrape the join flat when it's cured.

If it's exposed to direct heat then something cement based and dyed to match in a narrow joint is probably the best bet. Again it would be non structural.

You could reinforce the cold/hidden side with some fiber if need be.
jk

In reply to gethin_allen:

I think that would be beyond me, but JB looks like good stuff - how maleable is it? I would if could push it in to the cracks somehow.

In reply to iksander:

I've not used that exact product but it seems like plumbers weld, you break off a chunk then squish it about between your fingers to activate it and then squish it over the joint asap.
I guess you can force it in to the crack with a palette knife but the crack would have to be a reasonable width to get enough in to do the job.
But if it's not structural then you only need a filler. in which case you could even try something like Fimo modelling clay as you could probably find the exact colour match and let the heat from the fire cure the Fimo whereas you'd normally bake it in the oven.