title_body: When accounting for bloom, why is the common instruction to stir with very little water?
upvoted_answer: Blooming is the outgassing of CO2 (carbon dioxide) from the ground coffee in response to hot water being added.  The more recently the coffee has been roasted, the more bloom you can expect.  It doesn't make a huge difference ultimately if this is done quickly or slowly when you brew your coffee.  What I have noticed myself is that it's sometimes diffcult to predict how much foam is going to be produced when the water is poured over the grounds.  More than once I have misjudged the amount of bloom and made a foamy brown mess on my countertop.  If you just add enough water to wet the grounds first, you accomplish two things.  
  
  First, all the coffee is wetted at nearly the same time which better controls how the flavors are extracted, since different flavor profiles extract at different rates.  Sometimes adding all the water at once creates lumps of dry coffee mixed in with the bloom and wetted coffee and it takes a bit of stirring to get all that wetted.  
  
  Secondly, adding a small amount of water controls how quickly the bloom will occur. You'll get most of the bloom done well within the pot and you'll avoid the huge foam ball at the top of your brew that might overflow the pot (or AeroPress in my case), but really this is more of a technique thing than a chemistry thing.