Put approx two-thirds the amount of water, one third the amount of sand and all the lime followed by the remaining amount of sand and additional water until the required consistency is achieved. Mortar should be mixed for at least 10 minutes. Greater workability and better mortar performance is achieved with less water and longer mixing.(Mortars can be left to stand and fatten up for up to 1-3 hours depending on the mix: and tempered before use.)
Sand: For building, pointing, base coats and coarse finishes on renders / plasters always use a well graded sharp sand free of silt and clay #10-20 mesh down to #No 200. For finer work: use a fine well graded sharp sand free of silt and clay #100-150 mesh down to #200. (In some circumstances where very fine sands are being used, less binder will be required).
St Astier Natural Hydraulic Limes can be used for a wide variety of purposes.
Typical mix composition.