Need help using the refractometer

[GoldyCon]

I bought a refractometer off amazon last year to help me judge when the syrup is done. One issue I have so far is that the blue/white line seems to climb the longer you leave it up to your eye. I'm thinking that I might be putting too much liquid onto the prism and that it is flowing down the slope as I hold it up to my eye and maybe that is shifting the refraction a bit. Occasionally I get a sharp blue/white line but more often its a litte blurry and shows a gradient. Do any of you have tips or tricks for using this tool?

[DrTimPerkins]

I assume your refractometer has automatic temperature compensation? If not, it's only good at the temperature it is calibrated for.

In any case, the reading will keep changing until the syrup and the refractometer become isothermal (reach the same stable temperature). Put a drop of syrup on the glass, put the cover down, then wait for a minute before taking a reading.

[GoldyCon]

Thats a good possible explination that I will test. Thanks!