First a bit of history.

My Chimney has been pointed twice in th e10 years I've owned my house.
The first time about 9 years ago, the second about 3 years ago.

The first time, it looks like the guy just scraped out about 1/4" of
mortar and filled it back in. Now that thin layer of new mortar is
falling out. However, its still hard as a rock.

The second time, just a few spots were patched but the mortar used
looks like it has turned to sand and is disintegrating. I've been able
to remove a few bricks where this is happening.

I figure I can do just as good a job as the "professionals" who
screwed it up before so I'm going to give it a try.

The question I have is what type of mortar is used? I see the home
centers sell a type N mortar mix and a type O mortar mix. Type N being
stronger and is used for exterior walls and type O being weaker and is
sometimes called pointing mortar.

So far I have all the affected joints cleaned out to about 3/4 inch
depth, and all the old mortar has been cleaned from the few bricks
that I was able to remove. I ready to put the new mortar and bricks
back in.

-dickm