There are a few different methods around for making cold-brew coffee. Most of them involve a classic filter approach, where gravity slowly pulls the coffee through a paper, metal or cloth filter over time. Now when I say "time", I mean lots of it – usually over 12 hours. As we know, rate of extraction is proportionate to heat. Low heat means low energy which, put simply, means things happen more slowly. If you’ve ever poured cold water over a tea bag by accident, you will have noticed this. In the case of cold brewing, the coffee will literally be materializing drip by drip.