159 of 166 people found the following review helpful
Double check occasionally,
This review is from: Taylor Precision Products 9840 Cooking Thermometer, Digital (Kitchen)
One of the ongoing questions about these thermometers seems to be just how "instant" an instant-read thermometer is. The metal bit (actually, the bit inside the metal tube) has to physically warm up to the same temperature as whatever you're reading before it can send the signal to the display. It's going to take at least a few seconds. You'll never be able to jab it in the steak, glance at the number, and yank it back out a second later; you have to wait for it to warm up.
It appears that different reviewers have wildly different experiences in how long this takes, so you should be able to get an idea of how many seconds "instant" is for YOUR thermometer, and how well it's working in general, by running a quick calibration test:
Get a big cup of ice and add enough water that the ice starts to float. (You want as much ice as possible, but not packed solid.)
Find a clock with a second hand, and check the temperature on the thermometer (so you know what "room temperature" is). Stick the thermometer in the ice water. Watch the time until it hits 32 F (freezing temperature for pure water: salt water can hit 0 F). That should give you a good idea how long it takes to adjust down about 40 degrees in temperature.
It should stop pretty close to 32 F, but you may want to leave it in the ice water for another minute, to make sure that it doesn't keep on going -- that will let you know how accurate it is. Once it's stablized, you can take it out and let it warm up to room temperature again.
Put a pan of water on the stove to boil (a couple of inches of water is fine). When the water boils, grab your clock and turn on the thermometer to get an idea of what temperature it is now (this is to make sure that it's not still cold from the ice water).
Stick the thermometer in the boiling water. At sea level, pure water boils at 212 F, but as you get higher than sea level, the boiling temperature drops. The quick rule of thumb is two degrees for every 1,000 feet elevation, so if you're at 1,000 feet elevation, then you should expect to see water boil at 210 F, and at 6,000 feet, you might see water boil at 200 F. (There are other factors, like how pure your water is, so don't worry too much about a couple of degrees one way or the other.)
Watch the display and the clock to see how long it takes the thermometer to hit the number you expect for your area. That will tell you how quickly it adjusts and how accurate it is. If it takes 15 or 20 seconds to get from room temperature to boiling, then getting up to roast temperature (which is lower than boiling temperature) will probably take 10 or 15 seconds. Therefore, every time you check that roast, or turkey, or whatever, you'll need to allot 10 or 15 seconds to get an accurate temperature.
If you need something faster than this, then you'll have to pay for it. Laser systems (which read only the surface, not the internal temperature) and thermocouple systems (which work like this one, but are much faster: see the red or gray 'Thermapens' offered on Amazon.com by Baker's Catalogue) can easily start at five (or more) times the price of these inexpensive Taylor models.
Given the failure rate that other reviewers have noticed, I'd suggest you also double-check how well yours functions every now and again -- particularly before holiday dinners!