I have a Victorian fireplace surround - one of those that looks like marble but is really slate cleverly painted.
One of the bits has come off and I want to fix it back. Originally it was screwed on from behind, so I can't do that (unless I take the whole thing apart).
Can anyone advise what glue should I use for gluing this? It's a piece of slate about the size of a small book and weighing 1.4kg and with a (vertical) bonded surface of about 100mm x 100mm..
MS polymer (toolsatan, screwfux etc =A35odd for 310ml tube) and ingenious props etc whilst it cures? Just been using that to re-reattach limestone skirtings - tile adhesive failed, no-morenails failed, fingers Xed for MS polymer but it's convincingly sticky and sold as a stixall to all type product.......
Try the old fashioned, slow setting Araldite (epxoy resin) [1]. Follow the instructions on the packet, find a good method of supporting the piece until the glue dries fully (around 24 hours) - and the repair will last a very long time (even permanent).
[1] This will allow sufficient time for you to manoeuvre the piece into the correct position and to put any supports into place before the initial setting begins.
We had a marble hearth fitted a while back and had to cut off a few inches, The offcut looked like it ought to come in useful, but its uses have been limited by a rim piece stuck on at right angles. It looks like hot melt glue and it is much stronger than the marble, so I guess that is what I would use.
Standard hot-melt glues will soften easily if they get warm and will tend to creep slowly under load. Its also difficult to get a neat, thin glue line.
As long as you have clean and not friable surfaces the right way to go is epoxy (Araldite or Devcon or similar). As part of a project I measured the tensile load capacity of some epoxies a coupe of years ago. On glass-glass surfaces the very worst broke at around 20kg/cm^2, so it will have no trouble holding up your load. Will also tend to get stronger if its heated (within limits).
Make sure you mix the two components very thoroughly and hold the joint together while the epoxy hardens.
It certainly wasn't neat on the inside - not on view - corner. It is very hard and even trying to chip at the excess tends to break off bits of the marble surface rather than break the bond. Possibly it is epoxy - the 'butterscotch' colour, not clear - but it looks too uniform, but under the hearth it would not be expected to get all that warm - esp as it's only for decorative purposes.
However, ordinary Araldite does melt at relatively low temperature, so do check out their web site for the right version. Googling, "Araldite melting point" comes up with more info, and the 'Yachty' set seem to prefer 'JB Weld'.
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the blerb of which says it's good for 500F.
We used to cure test samples (overlap joint on aluminium strip) in an oven at 60C before pulling apart when cool. Can't remember what it gave at though - or how long we kept it at 60.
Also, when sticking bits on motorcycles with Araldite a waft over with a blow lamp would smooth out the excess and render it clear.
And while we are at it, isn't it amazing how, in donkey's years of producing the product, Araldite never have learnt to make caps that don't split and leave a horrible sticky mess in the bottom of the tool box. Even the 'hypodermic' type packs still seem to manage to split the end cap! Does anyone ever get to finish a tube?
Incidentally the Araldite blerb say's it is bisphenyl: which is, I believe one of the oestrogen mimicking chemicals they are phasing out of 'tin' can linings...
thank you all for your help with this. There is no problem with 'previous glue' becuase it was screwed on from behind originally, not glued. Clearly I'll need to roughen and clean the surfaces before gluing. I think I'll go the araldite route.
I agree about aradite caps - the tubes always end up coated in a slimy mess :-(
Is there any way you could use the screw holes to dowel the joint too? That should make the joint far more reliable. I was going to suggest threaded rod for the dowel but perhaps a wooden peg would be just as effective and easier if you need to dismantle it at a later date.
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