Refractometer re-visited

[David Woods]

Hi All,

I have searched all threads relating to refractometers but some are very old and I couldn't quite get all the info I needed. So..

Here are my thoughts - it seems a lot of brewers say that these devices are inaccurate and need a conversion tool for testing the FG. I was wondering if this is an idea to go with. What about just using the refracto tool at the end of fermentation when you may need to take many samples to test for brew for slow down / finish.

I feel that I would not really be too interested in absolute accuracy but the need to know that a brew is finishing - that way I can take numerous samples using almost no beer until it got low enough that I would then use the hydrometer to do the final accurate reading saving all that lovely beer!

Would you think this is a viable option as drawing off many tubes of brew for testing seems a waste to me - really don't want to take the chance of chucking it back in and infecting the brew even with sanitation. Was also thinking that this method would mean being able to get a cheaper device as all I am really looking for is the reading being stable over a few days.

I also see there are conversion tools to allow for the alcohol on the Google Play store and the Apple store.

Thoughts?

 

[kelper]

Yes, good idea!

 

[Brewed_Force]

I use a refractometer straight off to test OG, then after fermentation run the reading through a converter app to get the real FG.
Save faffing about with trial jars & hydrometers. I'm only interested in the FG to see if its as predicted by the recipe and to put in the bottom corner of the bottle label (ABV%).

 

[Ghillie]

You only need about 80ml per gravity reading with a hydrometer. It's no biggie; put it this way - if you rook 4 readings (which would be odd in itself) you'll only have lost half a pint.

I leave a couple litres of beer behind each brew, because I only rack the clearest from the top of the beer. So a few lots of 80ml drawn off for gravity samples isn't a dealbreaker.

 

[LED_ZEP]

I use the refractometer for wines along side the hydrometer to get a final abv if I'm not sure of the o.g. (if I've used a lot of fruit and not calculated the sugar contained within when taking the o.g.). It's also useful if you didn't take a start read.
Tested against known abv's it get to within 0.5%. Excel formula below:

=SUM((1.646*BRIX)-(2.703*(145-145/HYDROMETER)-1.794)

 

[David Woods]

Anyone got a recommendation where to get a reasonably priced refracto - or is it
just the usual suspects online!

 

[David Woods]

You only need about 80ml per gravity reading with a hydrometer. It's no biggie; put it this way - if you rook 4 readings (which would be odd in itself) you'll only have lost half a pint.

I leave a couple litres of beer behind each brew, because I only rack the clearest from the top of the beer. So a few lots of 80ml drawn off for gravity samples isn't a dealbreaker.

Point taken - but suspect with the refracto method I may be inclined to do more readings - and.... it's half a pint lost!!

 

[Ghillie]

Anyone got a recommendation where to get a reasonably priced refracto - or is it
just the usual suspects online!

I went cheap and don't regret it:
https://www.ebay.co.uk/itm/0-32-Bri...409782?hash=item2602c7dc76:g:XS8AAOSwoVZcBNrC

I often check it against my hydrometer and it's spot on, haven't even needed to calibrate it. Probably done about 20 brews with it and still going strong.

 

[LED_ZEP]

Anyone got a recommendation where to get a reasonably priced refracto - or is it
just the usual suspects online!

Tennerish on fleabay

 

[Ghillie]

Point taken - but suspect with the refracto method I may be inclined to do more readings - and.... it's half a pint lost!!

Understood half a pint is half a pint

As you brew more and more, and your technique improves and becomes consistent, you'll find you take less and less gravity readings during fermentation. So I wouldn't worry about loosing beer to the trial jar...

I can't remember the last time I took a reading during fermentation actually. Always test FG with a hydrometer when kegging as I'm 99% sure FG has been well reached every time. I don't rush my fermentations, and most last 2-3weeks - so reaching FG is almost a given.

 

[GerritT]

About 6 measurements with the refractometer during brewing (mash, boil, whenever it's warm), then 1 hydrometer just before pitching, 1 hydrometer after racking to secondary (=bottling vessel) and that's about it, that's what normally happens.

 

[chrisb8]

When I first started this was something that I thought about but now I have a regular routine I follow it amounts to 3 readings over the course of a 2-3 week process so it really is not much of a loss

 

[chrisb8]

Plus if you are inclined to you can drink the samples so it's really not technically lost. I'm not a fan of the OG sample though...

 

[PhilBrew]

Hi David

I've never found I could get my refractometer calibration quite right, to be able to rely on ... but then I've not really put the time & effort in to that, either .

So my "standard" process follows much as you suggested in your first post ... hydrometer reading for OG (with the wort for the sample either returned to the FV or mixed in with the yeast to "attemperate", as necessary) ... refractomer readings from day 10 or so, until readings are stable ... then hydrometer reading for FG (providing a cheeky early taster )

I might occasionally have a go at converting a refractometer (Brix) reading to a gravity reading, to give a ballpark idea of FG, but whenever I'd done that it's been a little out ... for some reason pale beers seem to measure higher gravity than they really are and dark beers lower, with my refractometer ... but now I've settled on this process, I doubt I'll ever bother calibrating any further.

Cheers, PhilB

 

[GerritT]

Hi David

I've never found I could get my refractometer calibration quite right, to be able to rely on <snip>

Cheers, PhilB

Put the kettle on, wait until the water boils and steam escapes.
Catch the steam with a wineglass in a way that you catch enough vapour to create some drops of water.
Just hold it above the spout, horizontally.
That water is pure. Use it for calibration.

 

[-Bezza-]

I take two hydrometer samples - one for OG and one about 2 weeks later to check my fermentation is finished. I don't worry about checking for stable readings over a couple of days and all that - if it's in the right ballpark for FG then I assume I'm ok. Two reasons why this works for me: 1) I then cold crash for another week, so there's a bit of time for some final bits of fermentation, and 2) I keg, so having gushers is less of a concern. The difference between 5.3% and 5.5% isn't worth worrying about.

First sample goes back into the FV, as everything is santised. Second sample goes down the hatch.

 

[Alex.mc]

I bought a cheapie off ebay as well. It's pretty accurate off the bat compared to the hydrometer, so I use it for OG, and then tap off a dribble when I think it's done to check. The conversion default on brewers friend seems pretty accurate for me, which I checked by comparing against the hydrometer. I don't bother with the hydrometer now as a half percent difference in abv is not something I could detect or indeed even worry about.

 

[David Woods]

Thanks for all the great help everyone. I plan on dry hopping when done then may cold crash so it should have plenty of time to complete. God knows what it will taste like but as long as it's not spoilt and has alcohol I will be happy. Bottling next - oh no! Likely will be looking at batch priming after doing the first brew bottle by bottle!

I will keep you updated as I do hate it when we are left in limbo on the outcome of brewing/tasting etc. This is one of many experiments I plan so I can learn as much as I can before going all grain at some point

 

[David Woods]

Thanks for all the great help everyone. I plan on dry hopping when done then may cold crash so it should have plenty of time to complete. God knows what it will taste like but as long as it's not spoilt and has alcohol I will be happy. Bottling next - oh no! Likely will be looking at batch priming after doing the first brew bottle by bottle!

I will keep you updated as I do hate it when we are left in limbo on the outcome of brewing/tasting etc. This is one of many experiments I plan so I can learn as much as I can before going all grain at some point

Sorry everyone posted in the wrong thread

 

[kelper]

I pour my hydrometer samples back in. The kit is sterilised so I see no risk.