All of my so called NIST-traceable lab thermometers were way off at both ice bath and boiling tests. But they were cheap and fast. I now use a Thermapen, but wish AmandaK’s upgraded RT600C was available when I purchased it.
Yes, that is the stated accuracy range. My friend who is a chemist checked mine in his lab and found it to be within .5 degree F across a wide temp range. Use what you like ! 
I have 2 in case I break one. They both read 32 in ice water and 212 in boiling water.
I have a couple of lab thermometers and they are accurate although they force me to think in degrees C which is painful.
You have a friend who is a chemist? I didn’t know they had the social skills to make friends. Maybe its just me after all.
Use what you like, exactly.
You’re a brave man. I’ve read too many stories of those breaking during use.
Unless you mash at 32 or 212, that test may not be accurate. You need to check them at mash temps.
I do like the ruggedness of bi-metal probe thermometers, but they are easily uncalibrated with use or abuse. Having a traceable calibration thermometer to check those bi-metal thermometers is imperative. On top of that, the bi-metal thermometers may not be as linear in their response as some other types, so having that calibration standard and calibrating at mashing temps is good practice.
With that said, those cheap electronic units that Sean Terrill mentioned months ago and Amanda pointed to above, seem to be a great deal and several are waterproof. I see that you can pick up a calibratable unit for $19 (Model: RT301WA) and its spec says its within 0.9F. That is pretty good since a much more expensive Thermapen is only slightly better (0.7F). Considering that the cheap unit is made by the Thermapen people, I would skip to the cheaper option without a blink!
My thermometer is just another part of my process. I don’t know if it’s exactly accurate at mash temps but it’s accurate enough. If a beer doesn’t attenuate the way I want it to on one batch, I just adjust on the next batch and I get what I want.
I went through six $20-30 digital thermometers in 2 years. Two were remote probe types that were horribly inaccurate. The
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others just quit after several batches-two while doing brewing demos at my lhbs. On those two brews the owner gave me dial thermometers to use and my attenuation was nowhere near what I expected. Maybe if I started off with a thermapen I would still be using it. Maybe not. Either way I’m done with digital thermometers.
After I switched to lab-type thermometers, my attenuation was a little off but I adjusted and dialed in and I am quite happy with my process and my beer.
You don’t have to be brave to use glass. Just careful. Like holding a newborn baby…
You gotta be brave to drive a car with some of the knuckleheads on the road but that doesn’t stop any of us.
Glass is our friend.
Big Al, I like to use a calibrateable bimetal thermometer. Every few brews I calibrate it at mash temps using a certified lab thermometer. Something to consider.
Went to Amanda/Sean’s website and saw there was a buy two for $16 each sale, so I got two. Going high tech. This will set back my efforts to think Celsius though.
+1 to Big Al’s way of measuring mash temperature. Although the temp reading may be off, as long as the measurement device is consistent, the net effect is that you just adjust the desired temp up or down to suit your desired beer characteristics. I suppose that the main deficiency would be that Big Al may need to ignore temperature recommendations from other brewers and base his mashing decisions more on his intuition.
But, calibrating to a standard does allow you to recommend and compare temps more accurately.
Tell ya what: if(when?) I break one of my lab(-style) thermometers, I’ll replace it with a certified lab thermometer. If(when?) The other one breaks, I’ll try a good bimetal thermometer. But it just wouldn’t be pragmatic to replace them before that since I’m happy with what I’ve got. I do understand that although my process works for me, my recipe may or may not be repeatable on someone else’s system. Then again, is any recipe truly transferable from one system to another?
Just priced the certified lab thermometers. Wow. Pricey.
Fyi, I built a holder for my lab-style thermometer. It’s just a piece of sheet metal(copper in my case) about 4-5" long bent to a hook on one end and a 90 degree angle on the other. The hook end hooks to the lip of my kettle/mash tun and the 90 end is drilled and fitted with a grommet just the right size to hold the thermometer. It holds my thermometer in the mash, safely out of the way, with the lid on. Because it lives in the mash, it’s instant read. Out of the kettle/tun I can hook it on something safely out of the way. I credit this idea to the Jan/Feb 2009 Zymurgy gadgets issue. Piece of scrap sheet metal was free and the grommet cost me 10¢.
Bought a refurb Thermapen (or open stock, whatever). Love it. Fast reading, and I bought it in bright green so I see it immediately if I place it in an odd spot while I’m brewing. Use it for cooking, too, and other stuff.
I use this one, from the makers of the Thermapen:
http://www.thermoworks.com/products/handheld/ecotemp.html
I find the alarm feature handy and the probe just sits in my mash so I don’t need to open the cooler to take a reading.
If one is calibrating using boiling and freezing, one needs to know how to make a proper ice bath, and know what boiling temperature is at their altitude and barometric pressure. That will give you a 2 point calibration, if the device is perfectly linear through the range you are good to go, but that linearity assumption often does not hold true.
Proper ice bath video.
http://www.thermoworks.com/learning/thermapen101_creating_an_icebath.html
You know how a tool you like to use seems to conform to your hand, and comes out as effortlessly as a carpenter pulls out his framing hammer from his tool belt? That comes from confidence in the tool, and that it will do it’s job very well. Why stop at asking for a good thermometer for checking the mash temp? Depending on your setup (mine is cheap 'n easy) shouldn’t the same thermometer be able to very accurately and very quickly and safely test the temperature of your hot liquor, sparge water, strike water, wort in regards to pitching temp, and hydrometer sample?
I’m kind of a nut for accurate notes, and hitting desired temps, but I can repeatedly quickly check temperatures with ease and confidence with my Palmer-Wahl TM 500 that Blatz recommended a few or more years ago, along with a compatible 18" (or is it 24"?) SS probe from McMaster-Carr.
Oh, the removable probe quickly detaches from the unit and the connection end sticks up above the top of a bucket full of Star San solution, so it is easy to wipe clean and sanitize too.
http://www.palmerwahl.com/product_home.php?itm=604
Now I’ll get off my soap box.
handles PH and Temp…same place you get the thermopen.
I think I like this option a lot, as I am looking for a good thermometer and a pH testing device. Thanks wort-h.o.g
sure thing. make sure to use the 4.01 and 7.0 solution for calibration - they calibrate based upon a typical measured ph in the range of 5.0. also ATC is good up to 140F, so for accurate PH reading you will need to cool mash sample slightly (10-15F)… Im not sure how to account for PH variance taken at typical higher mash temps in the 149-156F