Sandstone Pointing

[ssutherland]

I have some water ingress from cracks/failed pointing in a sandstone wall. As far as I understand I should be using a lime mortar for repointing based on a purely lime and sand mix but I keep seeing different mixes recommended, varying from 1:5 to 1:3. Assuming I can get hold of some lime can someone give me an idea for the correct procedure for mixing the lime mortar and the mix I should be using?

[welsh brickie]

Mix 4:1 sand and lime.You can buy a bag of hydrated lime from most builders merchants

[ssutherland]

4:1 it is then. I tried the big diy stores with no luck but I think I've now found a local builders merchants that stock hydrated lime.
Many thanks