As solid as they are, brick walls are not impervious to the elements and they eventually show signs of wear and tear. A frequent problem with brick walls, especially those from before the 1930s, is crumbling mortar. The process of fixing this mortar is called pointing (sometimes “repointing”), and it involves basic masonry skills.
Check out the age of the wall to be repaired. Prior to the 1930s, brickwork in America was done with lime and sand mortar mixes and softer bricks. If you point a soft brick wall with modern Portland cement-based mortar (which is very hard), you will cause cracking and spalling in the brickwork and create a much bigger problem. If you are in doubt, point it with a soft lime and sand mortar mix.
Scoop up mortar with a trowel and pour it into a mortar bag, or "cake decorator."
Repeat Steps 4 through 7 on small sections of wall until all of the soft and crumbling parts of mortar are pointed.
Allow the mortar to harden for roughly half an hour before returning to scrape away excess mortar with a stiff brush and the trowel.