Sorry for the simplicity of the question, but I asked Google and she didn't know. Stackexchange is my next stop.

I took a brix reading of my steam beer wort at 13 brix (~1.052 SG), but it was probably about 110 degrees.

  • edited! It was meant to read brix
    – Pietro
    Commented Aug 20, 2012 at 14:14

3 Answers 3


It's not usually necessary to cool - most refractometers have built in Auto Temperature Compensation (ATC) to correct for temperatures up to 30C/86F. However, for hot samples in a warm environment then some cooling may be needed.

When the ambient temp is cool (<20C/70F) the ATC will be sufficient and that the quantity of liquid is small and has a very small thermal mass compared to the body of the refratometer. So, it will cool quickly from mash temps, while only warming the refractometer by just a few degrees.

But if the ambient temp is close to the upper range of the ATC, then the additional sample may warm the body above what the ATC can handle. Then cooling is needed.

So, if in doubt, leave the refractometer for a few minutes. I've noticed a change of at least +0.5% brix after a couple of minutes when sampling hot mash samples, presumably because the body temperature rises above the level that ATC will correct.

  • 1
    ATC is meant to compensate for the temp of the refractometer, not the sample.
    – Denny Conn
    Commented Aug 18, 2012 at 20:25
  • 2
    Sure, but in practice it amounts to the same thing - it doesn't take long for the sample and refractometer to equalize. And should the body temperature increase a few degrees because of the warm sample, the ATC will take care of that.
    – mdma
    Commented Aug 19, 2012 at 6:52
  • I would second always letting the sample cool on the refractometer for a few minutes before reading, I've been burned by this before.
    – hartski
    Commented Aug 19, 2012 at 13:02
  • 1
    mdma, I'm not so sure about that. Ever tried using a refractometer in a 35F garage? If you don't keep it warm before you use it, the sample will cool but I still get an incorrect reading due to a cold refractometer.
    – Denny Conn
    Commented Aug 19, 2012 at 15:16
  • 1
    I have seen something similar, and I agree. You have to be sure the temp is within the range the ATC can handle. The refractometer usually includes a spec for the temperature range over which ATC will compensate - 10-30C/50-86F is typical, so 35F is too cold for the correction to work, which is why you need to warm it up to get an accurate reading. At room temperature, the ATC will work properly, and will also compensate for the slight raise in temperature created by the warm sample, but of course only if the equilibrium temp is below 30C/86F.
    – mdma
    Commented Aug 19, 2012 at 17:52

Just called Robinar, manufacturer of refractometer I have. Posed the temperature compensation question to them and the response is: when calibrating the tool (IE: putting distilled water on the glass) make sure that test/calibtratiuon water is the same temp as the product/material to be tested.


if your refractometer is with ATC, then you don't need to adjust.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.