Chimney Cap & Repointing Report

The chimney with lime mortar you gentlemen were so kind to advise me
on has been repointed with FJN's 1:2:8 mix. It has been in the high 80s to low 90s here with brilliant sun, so I am wetting it often.

Let me pause here to give you all a kind "Bravo!" for your useful insights and the kindness exhibited on the prior thread.

Some of the concave joints exhibit a bit of "alligatoring" in places, although it isn't widespread.

Two things stick in my mind.
One, there is a brick that was replaced on the chimney shoulder nearest the wall which is out of whack with the downward diagonal plane set by the rest of the bricks just enough to stand out visually.
I should have caught that in the process but I didn't.

Perhaps more significantly, the crown the mason fabricated out of cement and sand is now showing some difficulties 4 days after completion. The top would have been better had it been less flat. On the sides, the cap does have a taper out to the edge of the top row of corbelled brick. Without freeze-thaw problems here, I don't know that this presents a concern for face spalling. You may advise me on that. NOTE CORRECTION: The top row of corbelled brick is bordered by the cement cap on the top and a run of mortar on the bottom. The bottom row of corbelled brick is overlaid by a line of mortar on top and overhands into the air on the bottom.

Perhaps more of moment (or not), the crown shows evidence of cracking along the Eastern sunrise side and elsewhere. Exposure to heat and the fireball have done it no good early on. A few cracks have opened up at this stage to about 1/64" and when the crown is wet, a dark spiderweb of lines seems to predict more cracks may be coming.

Until the 28 day cure period is done, I'm not doing anything except keeping the structure wet. I've gone from misting it more frequently to about every 3 hours in daylight.

The question is whether this crown cracking from shrinkage is likely to pose a jeopardy at some point and, if so, how much cracking would that mean and what would be my response?

I'm reluctant to bang on the crown given some of the top rows of brick depend on the tuck pointing for stability. But if you counsel I might (after 28 days of cure) think on that and casting a cap with reinforcing mesh and fiberglass strands that extends 2" out from the chimney, that may be something within my attempting.

Other courses that I've found explained would be buying a stainless/galvanized cap that fits over the crown, has an outer drip lip and provides a roofed and enmeshed central structure to embrace for any future addition of a flexible flue liner; not cheap. People are pretty positive about some of the dedicated siloxane and other chimney sealers dealing with minor cracking. That the minimal quantity of the pricey chimney-specific compounds would coat every chimney on the block when I only have one seems ironic or savvy marketing.

Anyway, as always, I appreciate your time and thoughts. You seem like an island of right guys in the wild Internet frontier.