Baltimore brick is is often soft, though many formstoned buildings were newer and had harder fired brick. Another reason is the mortar joints are of lime mortar. Great material, but it has a life span, when exposed to the elements. Leaks occur.

The process of applying it is the same as Stucco. Expanded metal mesh is nailed to the brick, in the mortar joints. The Portland cement stucco mix is troweled on. Had the owners chosen smooth stucco finish people would not be concerned. Stucco is used all over the world and is a great way to protect the lesser looking cinder block or soft brick. The ides of making it look like stone is where the cheapness comes in. Flagstone was used in suburban houses in the 50s, it has a very period look. If you spend much time scoring the stucco as real stone, it is fairly convincing. This is how the Cardinal's residence is treated , just behind the Basilica. The guys who did many of the city houses had to work fast and score the joints before the cement hardened. A close look at most houses will show they were not good about making the vertical joints at the correct place to look real.