I just bought my first refractometer today I was reading the instructions. It has a temp correction chart, or you can take the reading at 20C or 68F without making a correction. My question is once you place a drop or two on the glass does'nt it change the temp. I mean if you put 74F liquid on the glass would'nt the glass cool it down some? I just want to use it as a quick referance to make sure I dont over sparge. Any advice or help is appreciated.