How exactly do you calibrate a thermometer?

[blucoondawg]

THIS is why I don't trust bulb thermometers. See the gaps?

I didn't notice the gaps like that in the one that came with mine however I still don't trust it, I calibrated it, as you must do, by using my room temperature and another thermometer which I trusted to be close, however when compared to the one I just bought for 3 dollars and change from Fleet Farm, it is 8 degrees low at 99-100, so when I had my incubator at 99.5 with that thermometer on my first run, I was actually at 106-108! I won't use that cheapo thermometer again.

 

[blucoondawg]

THIS is why I don't trust bulb thermometers. See the gaps?

I have a similar cheapo thermometer that came with my Farm Innovators model and that is what I used on my first attempt, I don't notice the gaps like that in mine but it is not trustworthy at all, I calibrated at room temperature with another thermometer but when it gets up to 99-100 it is reading about 8 degrees low so I was actually incubating at around 107 or 108 degrees. I won't use that thermometer again, the $3 and change one I got from Fleet Farm seems to be right on, I also have a $.99 cent suction cup one from WalMart that I wasn't trusting until I compared it to my new one and it was dead on, so now I use those 2 and a cheap stick up hygrometer for an amphibian tank.