I’m wondering if you can use an infrared thermometer to read the temperature of fermenting beer in a carboy (through the glass). I can’t think of why it wouldn’t work, unless the thermometer needs an opaque surface for an accurate reading. Anyone do this?
I used to use one on my buckets. Seemed to work OK but was never confident that it was accurate.
IR thermometers are really picky. To be accurate, you need a non-reflective, black surface.
When working at a chemical plant, we painted black spots on each tank to measure their temps with IR. The same could be done on your carboy. A few strips of electrical tape might do the trick.
Good info!
I love my infrared gun, but I’ve yet to trust it for anything aside from mash.
I use mine for AC vents etc. After experimentation I’ve found it to be useless for the mash since you need to read the interior not the surface- which won’t read true. Always significantly off (cooler).
I figured reading a hot wet surface is even more problematic because of evaporative cooling at the surface.
I use a Fluke 62. It’s not nearly as accurate as a lab thermometer but gets you in the ballpark. A non-reflective surface is best.
Check out this thread.
http://www.homebrewersassociation.org/forum/index.php?topic=11213.msg139441#msg139441
Infrared thermometers see the infrared color of the surface they’re measuring, and interpret that color as a temperature. The more in focus the surface being measured is, the more stable the readings will be. Not necessaily accurate, but good for trending, and especially finding heat leaks.
As euge said, internal temperatures are problematic.