I've been searching for a good thermometer for home brewing for some time. When we found the True Brew floating thermometer it seemed like the solution to the shortcomings of other thermometers. The temperature range is within what I need for beer brewing (unlike many candy thermometers which are designed for much hotter cooking) and it floats in the wort taking a constant temperature. Sadly, this was not the solution we had hoped.
Although the floating feature is nice, I found that the reading is often inaccurate as the weighted end sinks the tip of the thermometer down to the bottom of our stock pot where the range top sent the reading higher than the actual temperature in the heart of the pot. This was easily remedied by balancing the thermometer on the grain bag while it steeps.
Unfortunately -- and more importantly -- the thermometer is also apparently prone to *breaking*. During my most recent brewing session, the temperature in the pot reached 170° and the tip of the thermometer broke, spilling glass and steel shot (the weight that pulls the end down) into my wort. Looking up the problem online, it seems to have happened to a number of different people under similar circumstances. Fortunately, the alcohol (not mercury) *thermometer* portion remained intact, and it was only the shell casing (that enables the device to float) that broke. Sadly, that's enough to pollute whatever you're cooking with glass and shot.
We called a friend who runs a brew supply store and he assured us that his distributor tells him that the contents of the thermometer are completely non-toxic, but it's still unacceptable that a cooking thermometer (or its casing) would be so fragile as to break at a temperature in the *middle* of its reading range.