So, before I ever brewed batch one with steeping grains and extract, I learned, DO NOT steep or mash above 170 degrees; you'll extract tannins, and while some tannins are appropriate in wine, they sure wouldn't be a nice enhancement to your beer! Now I'm getting into all grain (awesome!), which leads me to read about such things as decoction. So the question is: how is ok to boil part of your mash, but mashing or steeping over 170 is sure disaster as that tannins will be released? (same thing in stepping, adding boiling water to raise mash temp, obviously well above that 170 mark..??). What am I missing?