Hi James and thanks for focusing on the question asked. While I do
appreciate the random "discussions" that erupt among interesting people
of all viewpoints on the internet, there is indeed a question on the
table regarding fireplace safety and the need (or efficacy) of sealing
the "rough" patch of mortar in the firebox. In answer to your query,
the smoke blew out shortly (1 - 3 minutes) after lighting the fire.
The fire was lit after "heating'" the flue by burning approximately 5
rolled newspapers and holding them above the prepared fire.

Not to "fan the flames" so to speak, but as far as the environmental
concerns voiced regarding lighting a fire, I'm sure any gaseous
emissions from the 5-10 small fires I build a year is a pittance in the
grand scheme of things compared to the enormous forest fires which
erupt in California (and other western states) on a bi-annual basis
thanks primarily to their environmentally unsound practice of banning
logging, resulting in overgrown forests which fuel uncontrollable
burns.

Yes, its true - wood fires are "unnecessary". So too are gas fires.
Or artifical incense. Or Christmas trees. Or driving our cars. Or
wasting energy and natural resources constructing snow boards. Or
using animal hides to make leather belts and shoes. Or a million other
things. If I was interested in debating that, I would have posted the
message to alt.altruistic.babble - not misc.consumers.house.