You don't indicate the age of the structure or type of brick used.
IF you put high compressive strength mortar with very old bricks,
you will destroy the bricks. The strength of the mortar is
subject to the ratio of Portland, lime, and sand. The color is
most affected by the color of the sand.

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______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)




"dicko" wrote in message
...

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