The garden wall on a new build estate had been pointed with very weak mortar. Most likely caused by not enough cement being put in the mix or it being laid in sub zero temperatures. The customer called us to come and fix it.
To make pointing mortar, use a standard 4 parts sand to 1 part cement mix for modern bricks, or a 3 parts sand to 1 part NHL 3.5 lime mix for older, historic properties. Combine dry ingredients thoroughly in a mixing tray before slowly adding water until it reaches a workable, crumbly-yet-sticky consistency.