Refractometer

Howdy -

I have 4 brews under my belt and am constantly looking to upgrade each part of my process. (Already thinking of a 27-gallon conical fermenter.) Anyway, I've used the hydrometer for these batches, but I'm looking to get a refractometer. Looking at both kinds, the "look through" kind, and the digital display kind.

One point someone brought up in a review for a refractometer was that in general they don't work well for determining ABV because the measurements after it starts producing alcohol will be off due to the alcohol content.

Is there any truth to this? Or is this user way way off?

Cheers,
Kojones

 

To use a refractometer to get FG, you need to know the OG and apply a correction factor. I use Beersmith's refractometer tool to correct mine. It's not entirely accurate, but it's close enough for me.

 

Kojoles,
I am a lot like you and have gone through several "upgrades" and always looking for more. I jumped right up to the refractometer (bought on ebay -great way to save money at this particular piece). However, I have come to realize that relying on the refractometer post fermentation to get my ABV is not wise. The numbers are way off. For ME the refractometer's place is during the boil and just prior to going into the fermenter and then its solely hydrometer to measure gravities.
Hope this helps.

 

It's also good for measuring pre-boil gravity. That helps you know if you need to add DME or water in case you are brewing AG and missed your numbers.

 

+1. It can also be used to modify the boil to increase/decrease your final volume so you can hit your projected gravity.

 

It's definitely worth it to have just for the pre-fermentation portion of brewing. After that, the wort is generally close to proper temp and taking a hydro reading is nearly as troublesome as trying to get it while actually brewing.

That said, I do use mine for FG readings and the several times I compared to my hydrometer and applied the formula to convert the measurements, it came out dead even. I've heard rumours that a higher than average beer may not read correctly, but I don't think I've made anything over 1.070 since I bought mine.

My last batch is in the fermenter and fully fermented, so I should go out and do another comparison.

*Note - I always check the calibration before each use, and always cool the tiny sample a few minutes before measuring.

 

I got a refractometer to brew all grain, and I must say that it has been very useful to monitor the mash gravity. I made a comparison with the hydrometer pre-boil and post boil, it was spot on.
But I am not sure it is useful for extract or partial mash to check the gravity often. I know I did not want to worry.

BTW, BobbyM has a great deal on refractometers. It is the same sold as AHS, but 20$ cheaper. Unfortunately it was too late when I saw this...

 

I purchased a refractometer specifically for the purpose of not having to take hydro readings. My buddy and I are starting to get into AG brewing and we want to do a number of small 1-gallon batches to work on two different recipes. Taking a hydro reading off of a 1-gallon batch would mean that a significant portion of the wort would be wasted just on tests. I hope that the conversion formulas hold up.

 

There are many excellent online calculators to steer you through the ferment process when using a refractometer. I think there is a learning curve to using one exclusively. I used to take samples from my hydrometer and check them with a refractometer. I would get some unusual readings at first, but over time, with practice, I got to the point where I never use the hydrometer anymore. I know when I get a reading I can trust it.

 

Thanks for all the discussion! To summarize, it sounds like a refractometer is great and very accurate for pre-ferment (no alcohol). However, one company sells a unit with a calculator on it's webpage for conversion to compensate for alcohol content. (Makes sense that this is possible knowing the OG and the FG and throwing in a constant compensation for alcohol based on the difference in readings.) And, if all I'm wanting to do is determine when to bottle/keg through the slow-down of SG changes, then the refractometer will work consistently on that.

Cheers,
Kojones