Tuckpointing a Historic Chimney. HELP!
At some point somebody thought it would be a good idea to paint the red brick…red. So, you are looking at red paint rather than red brick.
As a reader of Old House Journal since the 1970s (yes, I really am that old), I have known for decades the dangers of repointing, even though until today I never had a practical use for such knowledge. You see, most masons will just buy the type mortar they always use and fill in all the empty spaces.
THIS IS BAD.
Because, old brick is rather a different thing than post-WWII brick, in that it is much softer. But modern mortar is very hard. This is fine with modern brick, but will prove a disaster with old old old brick. Like my 122-year-old brick. Mortar which is too hard will literally destroy the brick. Mortar should be just a bit softer than the brick itself.
The problem for me is:
- What kind of mortar do I need?
- Where the hell do I buy it?
I found this online:
Mortar comes is types. Type M, S, N, O, K, and L.
Type M is the strongest and hardest and contains the highest percentage of Portland Cement while Type L has no Portland Cement and is the softest.
Type O and Type K are recommended for most historic masonry applications. However, most masons are not aware of this.
So, it would seem that I would be good with Type O or K, right?
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