Q.1.Is there a recommended mix ratio, sand to cement for pointing stonework please?
Q.2. There's a bonding solution, that you apply to brick and stone, which helps the mortar stick. Can anyone remember the brand name? TIA.
A1 what sort of stone? Mix should be weaker than the stone...
A2 pva ?available everywhere no need for a "brand"
Jim K
Many thanks Jim, PVA added to the shopping list.
The stone may be called 'skillet' but I'm not sure. It's a mid terrace house, built 1840s for Cornish miners.
I think the garden walls are similar. About 2 feet thick, made up with uneven layers and then dressed with mortar.
Certainly not as hard as granite.
p.s. I'll scrape the loose paint away and take pics of the 2 areas worst affected. Will post pics about 3 pm -ish.
Buy Mortars, Plasters and Renders in Conservation by John Ashurst (availble from SPAB) The answers to your questions are as follows
3 parts sand 1 part lime PUTTY not the bagged c*** put the mortar in a gap at least twice as deep as the width of the mortar have it no further out than the horizontal part of the pointing gap EVEN I F THIS MEANS IT IS RECESSED BECAUSE THE ARRIS IS WORN ROUND ie you need ke ep the width of the visually exposed white mortar the same as the original gap and not spread it wide around a worn arrisAvoid any glues be the SBR or PVA completely "pointless" and destructive of the purpose of the pointing which is a sacrificial water exchange mechanis m to protect the stone Chris
original probably lime based mortar ... self healing in wet ... You could do this with 1:1:5 lime:opc:sand
You can buy pre-mixed Lime pointing mortar, never used it though:
Work that like should be done in lime & sand. 3:1 is the usual mix. Sometimes people add 5% OPC, but its use is often not recommended.
Looks like white lime, a light sand and some black grit of some sort.
Don't know what sort of paint it is, paints on stone can cause flaking due to freeze-thaw damage. Lime based paint avoids that - and is easy to use, and very cheap. But not as long lived as the better modern masonry paints.
NT
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