Is hydrometer temperature calibration accurate?

[techtone]

My last few batches I have only taken og reading when the wort is about 60-70 C. I then converted it and didn't bother taking a later reading closer to 20C.

I thought my efficiency was improving and was finally getting good results from the Bairds malt. However yesterday I took a reading (having stirred well) at 66C of 1.028 which according to BrewMate converts to 1.047. However, this time I decided to take another reading at about 22C and it was down to 1.040.

This is quite a difference and reduces calculated efficiency by 10%.

Is 66C just too hot to get a reading to convert even though the calculators accept it?

(hydrometer calibrated at 20C)

[jimp2003]

The further you get from 20 degrees or so the more inaccurate those conversions tend to be. I don't trust them until the sample is under 35 degrees C.

I bought a refractometer for this reason but even when using one of those you need to make adjustments.

[Belter]

I dont have any plans at this stage to purchase a refractometer but it's something I'm thinking about for the future. Is there a tried and tested refractometer that most homebrewers use? I've seen them for £1000's.

[darkonnis]

Wouldn't bother with a refractometer, this is something thats been discussed quite a lot and there is as much evidence for, as against. Refractometers come with their own issues which means you won't necessarily end up with a tool any better than a hydro.
Take a sample out the boiler straight away, let it cool then test it while the rest of the brew cools down. The hydrometers are accurate to about 30ish C after that just take it as a rough guide. If efficiency is an issue then you really do need to let it cool. The money you might spend on a refractometer might be better spend on something to increase your efficiency. Just my opinion of course.

[sib67]

I would definitely get a refractometer - a cheap one will do, you can get them for about £20.

[sib67]

I would definitely get a refractometer - a cheap one will do, you can get them for about £20.

I only use mine for hot wort from the underback and copper, which is the only time that the extreme temperature is a problem. A hydrometer is best once fermentation has started.

[gregorach]

I could never get temperature correction for a hydrometer to work anything worth a damn. You either cool your sample to somewhere fairly close to the proper temperature, or buy a refractometer. I wouldn't be without mine...

[techtone]

Thanks for the replies. I'm happy to wait until it cools, from now on. Was only doing otherwise as I didn't know better. As for the efficiency issue - Bairds - enough said.

[bigdave]

I'm starting to wonder if there's 2 class of hydro...

1) Hydrometer
2) Hydrometer shaped object

Mine (bought from wilkinsons) must fall into the second class as every brew I've used it for has started at 1.054 and finished at 1.000

[darkonnis]

Well some are more accurate than others, you cannot expect a £4 wilkinsons own hydro to be as accurate as Stevenson & Reeves £20 jobs. It largely depends what you need it to do. If you just need to take a rough "starts here - ends here" then the cheap one is as good as any. If you're bothered about actual %% and tailoring your brew to certain styles or certain needs then buy a more reputable one.
I have a coopers one and a stevenson reeve one, both are accurate to 0.001 of each other which is enough for me, I also find temp correction isn't accurate but if you KNOW how much it is out, then you can take a guess. Like I have mine written down for wort at 60c as straight out the boiler it cools to that while heating the bowl its in. I only have it written for 1.036 or so as I made blacksheep bets bitter quite a bit but still I know what I'm looking for. Nothing stopping you doing the same for a known temperature and wort of 1.010 - 1.020 - 1.030 etc etc or you as i said before to the OP just let it cool. there isn't much you can do about it once you finish boiling anyway.

[sib67]

there isn't much you can do about it once you finish boiling anyway.

I disagree. Always aim to be slightly over rather than under, then liquor back to get to your desired OG.

[darkonnis]

Well thats upto you, but then you'd have to plan to be over than under in the first place and I'd rather plan to be on the money. And failing all else I just accept it as it comes instead of tinkering with something which might just turn out better.