Sandstone/Upvc joint

[Cadona]

Going to be installing upvc sliding sash windows which sit behind the sandstone mullions. Over the years the mullions have their edges broken off by previous pointing etc. I now need to 'square up' the edges to accept the thin bead of low mod silicone sealant round the new window frame. Any suggestions as to a durable sandstone patching routine, which will be overpainted? thanks..C

 

[pinenot]

Personally I would fix with a sympathetic coloured epoxy, if edges are badly chipped/worn, and forget the silicone and plump for a contrasting polysulphide, not painted, to allow for movement, paint will inevitably crack, almost within weeks. Either go for a contrasting seal or same colour as you would have painted...pinenot

 

[Cadona]

Thanks for that, I forgot to mention that the mullions are painted so it wouldn't matter what colour the repair was. What epoxy would you suggest pinenot?

 

[pinenot]

Which ever of the concrete/stone repair epoxy resins or putty your local national DIY builders merchant stocks, I myself have no preference, but I know Wickes do Cementstone, for instance...pinenot

 

[Cadona]

Thanks mate...I'll have a look around, see what they have...