I'm not sure what your product looked like, but I closed up a chimney on a previous house by chipping out the top clay liner and then inserting a flat piece of rock over the hole. I think used mortar on top of the rock to smooth the patch with the rest of the cement cap.

I then used a black polymer type stuff from Home Depot/Lowes that cost less than 20 bucks to "paint" the top of the cement cap, thereby sealing the whole thing.

Is your stuff somehow different from the Homne Depot stuff?

Switching,

This would be a different product. The product I used was intended to protect the crown of the chimney from weathering and for waterproffing. If you do a goggle search regarding a "flexible crown" you'll see what I mean.

Talk to you later, rredogg

Yep, the stuff I used was also specifically for sealing masonry. I looked at the stuff you bought, and the only advantage I could see over the stuff I used was that it came in colors other than black.

Other than the color, the funciton seemed to be the same.

So I guess I'm adding this note for anybody out there who wants to seal the top of their chimney cap and doesn't care that it's black -

You can get stuff cheap at Lowes or Home Depot that will do the job as well as the expensive stuff.

I recognize that this thread is from 05 but i thought i would add some info for those of you who are repairing masonry chimneys. The Flexible Crown product from Weathertite Idndustries has a 15 year warranty. The black tar like products from hardware stores will get hard over time and probably crack. I would look closely at the warranty before putting anything on my house.