title_body: Does it make a difference whether the moka lid is open or not?
upvoted_answer: So what I've been taught is that you should keep the lid open while brewing. This is so you can watch the progress of the extraction, and cut the heat at the appropriate time. It gives you much more control over your brew this way - for example, I cut the heat (and run the base under the cold tap for larger pots) as soon as I see the coffee running from the spout turn lighter, rather than waiting for the gurgle.
  
  However, as for lid open/closed during brewing, I don't imagine this has any effect on the extraction. The amount of heat lost will be tiny in comparison to other variables.