I have an older building that I am prepping for painting here in San Diego.  The lower story is stucco, built about 1940.  Since the last paint job (about 12 years), much of the stucco has developed patches of exfoliation–sort of blisters of crumbling stucco under the paint.  Most of them aren’t too deep; they vary from just a surface layer to about 3/8 inch.  I expected this near the ground, but these are as high as eight feet above the foundation.  In most cases, there is no possibility of water getting into the wall from leaking plumbing, roofs, etc.  

My plan is to just scrape & brush off the loose stuff, prime it, and patch with stucco patch, then prime again and paint.  Will this take care  of the problem, or do I have to treat the crumbling areas with something else?  One painter suggested an acid wash to begin with, but I don’t see what this would accomplish.