Several posts deal with the use of minimum smoke, just a puff, to
work hives easily. It is obvious that bees do not pour out
massive clouds of pheremones compared to the puff of smoke, so it
can be inferred that the smoke, even if one puff, would mask at
least the alarm pheremone. And, using the same logic, if the hive
on fire trigger is smoke, then it would only take one puff at the
entrance to trigger that reaction.
Either way says use minimum smoke. It also answers the question
of why wait for a few minutes to work the bees. You are waiting
for the smoke to dissipate in the hive so most get the word. My
guess, also, why I was taught to crack the lid and smoke the
inner cover is impatience. We don't wait the few minutes to let
the entrance puff to do its work but want to get right into the
hive.
Bill T
bath, ME
mcmanus wrote:

 I add a drop or two of vanilla
> extract. This also quiets them down by changing the smell of both to the
> same smell,