title_body: Generating crema with a moka pot?
upvoted_answer: Moka pots (or stove top percolators) usually produce a pressure of around 1.5 bar, while most coffees require a pressure of at least around 6 bar for a crema to appear. However, there are some Moka pots with a special valve (called Cremator) which helps creating more pressures and thus produce a crema.
  
  By the way, a real Espresso has to be brewed with a pressure of 9 bar ± 1, according to the Italian National Espresso Institute, so it can't be brewed with a Moka pot.