Refractometers and temperature compensation

[Galena]

I am considering a refractometer, I have read another thread on here but am wondering about the ATC, all the ones I can find are up to a maximum of 30 deg C. I thought one of the main advantages of a refractometer over a hydrometer was being able to quickly check the gravity of the wort without having to cool it to room temperature.
So can they be used at mash temperatures?

 

[Buffers brewery]

I use mine (only) during mashing. I haven’t checked but take the view that the sample size (mass) is so small compared to the size (mass) of the refractometer it cools pretty quickly. I always check OG before pitching yeast with a hydrometer as you can’t use a refractometer to measure FG of beer without a lot of faff.

 

[St00]

I use a refractometre pre-fermentation. During mash & boil I stick the wine thief in the freezer. It chills down easily within 10 minutes or so. I saw Gavin on the Homebrew network YouTube channel do it and I've used it ever since. No use to you if it involves traipsing up and down stairs, but we have a freezer in the garage in which I brew.

 

[Galena]

I use mine (only) during mashing. I haven’t checked but take the view that the sample size (mass) is so small compared to the size (mass) of the refractometer it cools pretty quickly. I always check OG before pitching yeast with a hydrometer as you can’t use a refractometer to measure FG of beer without a lot of faff.

Presumably though you can take daily readings to check when fermentation is finished when readings are consistently stable, even though it may not be an accurate SG ?

 

[Galena]

I use a refractometre pre-fermentation. During mash & boil I stick the wine thief in the freezer. It chills down easily within 10 minutes or so. I saw Gavin on the Homebrew network YouTube channel do it and I've used it ever since. No use to you if it involves traipsing up and down stairs, but we have a freezer in the garage in which I brew.

Cheers I will check that out

 

[Buffers brewery]

Presumably though you can take daily readings to check when fermentation is finished when readings are consistently stable, even though it may not be an accurate SG ?

Good question, don’t know the answer. Depends on the variation of the refractive index of the solution with differing amounts of sugar (decreasing) and alcohol (increasing).

 

[RichardM]

I use mine (only) during mashing. I haven’t checked but take the view that the sample size (mass) is so small compared to the size (mass) of the refractometer it cools pretty quickly. I always check OG before pitching yeast with a hydrometer as you can’t use a refractometer to measure FG of beer without a lot of faff.

You can use the refractometer to check the OG before pitching. It's only when the wort has turned to beer and there is alcohol present that using a refractometer becomes a faff.

 

[RichardM]

Try reading this if you want to get really geeky about measuring specific gravity Hydrometer? Refractometer? Or something better? - Home Brew Forum

 

[Drunkula]

If you're using a pipette have a glass of cold / ice water and stuff the bulb in it like Gash Slugg does. If I take readings and put it on the window hot, or just dunk the refractometer in then it'll climb up a bit over 10 minutes say 11.2 would go to 11.6 or something.

 

[Galena]

If you're using a pipette have a glass of cold / ice water and stuff the bulb in it like Gash Slugg does. If I take readings and put it on the window hot, or just dunk the refractometer in then it'll climb up a bit over 10 minutes say 11.2 would go to 11.6 or something.

Yes I have a pipette so that shouldnt take long, cheers

 

[AdeDunn]

I used mine for checking SG during mash steps only, never ever for post ferment. As other have said, let your sample cool to room temp before you check it. It was good, as used a much smaller sample than I'd need for a hydrometer reading which cools in a fraction of the time, so I'd only use my hydrometer for OG and FG (don't use different equipment to do each of these, because then you introduce a margin of error from equipment margin of error.... Where using the same piece of equipment you have the same error on both readings, so get a fairly decent idea of the ABV at the end with less error, ish, maybe. ).

 

[Galena]

So what about checking the gravity with alcohol, why is putting the Brix reading from the refractometer into a calculator not accurate enough for FG?

 

[RichardM]

So what about checking the gravity with alcohol, why is putting the Brix reading from the refractometer into a calculator not accurate enough for FG?

Because the refractometer is calibrated for wort. Light refracts differently when there is alcohol present and having to do calculations to correct for this is a faff, it's easier just to use a hydrometer.

 

[Galena]

Because the refractometer is calibrated for wort. Light refracts differently when there is alcohol present and having to do calculations to correct for this is a faff, it's easier just to use a hydrometer.

But when you say it is a faff, it seems to me (I stand to be corrected) all I need to do is put the OG and the current reading in Brix into a calculator like Brewers Friend or Brewfather and it does the correction for you and gives you the gravity? What could be simpler? What am I missing?

 

[BackToBasics]

But when you say it is a faff, it seems to me (I stand to be corrected) all I need to do is put the OG and the current reading in Brix into a calculator like Brewers Friend or Brewfather and it does the correction for you and gives you the gravity? What could be simpler? What am I missing?

I much prefer using a refractometer and, as the reading is being recorded anyway, putting the Brix reading into a calculator first isn't a huge issue.

My only concern at the moment is that I got refractometer after breaking my hydrometer so I've not yet been able to compare the calculated value against a hydrometer reading so I'm not sure how accurate the calculators default settings are. Doesn't really effect much other than calculating ABV as I'm just looking for a constant reading for end of fermentation but I do like things to be accurate.

 

[Galena]

I much prefer using a refractometer and, as the reading is being recorded anyway, putting the Brix reading into a calculator first isn't a huge issue.

My only concern at the moment is that I got refractometer after breaking my hydrometer so I've not yet been able to compare the calculated value against a hydrometer reading so I'm not sure how accurate the calculators default settings are. Doesn't really effect much other than calculating ABV as I'm just looking for a constant reading for end of fermentation but I do like things to be accurate.

I have just ordered one and want to use for pre and post boil gravities in case I need to adjust and for tracking end of fermentation rather than calculating ABV which is easy enough with a hydrometer, I will do some comparisons though as I go on. Thanks

 

[SteveB.]

I use a refractometer for mash gravity measurements so I can tell when the conversion is finished. It's such a small sample, a few drops, that its cools almost instantly when dropped on the refractometer glass. I also use it to measure the SG of the wort after boiling/ cooling in the fermenter. I track gravity during fermentation with an iSpindel so no opening the fermenter and it's obvious when fermentation has ended. The iSpindel is calibratd against the refractometer so is pretty accurate.

 

[Galena]

I use a refractometer for mash gravity measurements so I can tell when the conversion is finished. It's such a small sample, a few drops, that its cools almost instantly when dropped on the refractometer glass. I also use it to measure the SG of the wort after boiling/ cooling in the fermenter. I track gravity during fermentation with an iSpindel so no opening the fermenter and it's obvious when fermentation has ended. The iSpindel is calibratd against the refractometer so is pretty accurate.

Hopefully mine will arrive before I start my next brew, I don't have an iSpindel so will try and calibrate the refractometer against the hydrometer. It just galls me draining off so much beer for each gravity check and I don't want to risk pouring it back in, I am hoping a refractometer can tell me when fermentation has stopped.

 

[BackToBasics]

I use a refractometer for mash gravity measurements so I can tell when the conversion is finished. It's such a small sample, a few drops, that its cools almost instantly when dropped on the refractometer glass. I also use it to measure the SG of the wort after boiling/ cooling in the fermenter. I track gravity during fermentation with an iSpindel so no opening the fermenter and it's obvious when fermentation has ended. The iSpindel is calibratd against the refractometer so is pretty accurate.

I've got an iSpindel waiting to be put together so we'll have a similar setup once I get it up and running. Good to hear that it all works okay.

 

[Buffers brewery]

Hopefully mine will arrive before I start my next brew, I don't have an iSpindel so will try and calibrate the refractometer against the hydrometer. It just galls me draining off so much beer for each gravity check and I don't want to risk pouring it back in, I am hoping a refractometer can tell me when fermentation has stopped.

Let your brew ferment for at least 10 days then measure SG. Leave another 2 days and repeat. 9 times out of 10, fermentation is well finished and the 2 readings are the same and you're good to go minus 200mls if beer