Originally Posted by omokoro
Research decoction mashing, no need for a thermometer.
Don't you still need to mash in at a certain temp. and then know when to mash out when decocting?
Plus, decocting was a solution to poorly modified grain (and maybe not having readily available thermometers). It takes at least twice as long to do as a traditional infusion mash, so if your time is worth anything at all, a thermometer is a MUCH better solution.
I agree with everyone else - buy a thermometer - There is a reason that every brewery in the world probably uses them. However, here is an article that touches on temp. control in brewing hundreds of years ago in the absence of thermometers if you are interested in making your brew day more difficult and far less accurate, or simply recreating a historical brew day.http://www.breweryhistory.com/journal/archive/121/bh-121-066.htm