Tuesday, September 2, 2008

I Love My Refractometer

As I grow as a brewer, I try to find ways to refine my process. This can sometimes be a daunting task since I am expanding my system and abilities all the time. One piece of equipment I cannot live without is my new Refractometer.

What is a Refractometer?

A Refractometer is an instrument that measures the bending of light (refraction) through a liquid. In brewing and wine making, it measures the density of sugars in the solution.

How to Use It

The issue with using a Hydrometer is that on must take a large sample of wort to get a reading. Once you get the reading, it is not recommended to pour that beer back into the main wort because it might introduce infections. If you like to check your specific gravity (SG) several times during the boil and fermentation, you could end up losing several pints before your beer is ready for consumption.

A Refractometer is wonderful for one reason. It only takes a couple drops to get a reading. Readings are usually in Brix, but with some simple math, it can be converted to SG easily.

Simply place a few drops of wort onto the lens and then look into the eye piece. A reading in Brix should appear. To convert this brix reading to specific gravity, simply multiply by 4. There is a more accurate formula, but the multiply by 4 formula will get you pretty close. If your Refractometer reads 10 brix and you multiply by 4, you get 40. This means your wort is 1.040. The actual is 1.039, but I said the simple math would get you close.

How to Use a Refractometer While Brewing Beer

Using a Refractometer while brewing is one of the better enhancements I have made to my brewing process. It allows me to make simple adjustments, on the fly, while brewing.

It is important to buy a Refractometer with ATC (Automatic Temperature Compensation). This will help with readings in various room temperature ranges. Most refractometers are ATC, but incase the one you got is not, use a temperature compensation chart.

When the mash conversion is complete and my wort is heating up, I take a reading. This gives me my Pre-Boil Gravity (PBG). I then take a reading about 30 minutes into the boil to see how things are going and to see if I am on the way in hitting my Original Gravity (OG). I then take a reading with about 15-20 minutes left in the boil. This is the most important time to adjust the brew. If it looks like my OG is going to be too low, I can add some dried malt extract (DME). If it looks like my OG is going to be too high, I can add a little bit of water.

All I need to do it take a tiny sampling (2-3 drops) of the wort to get my reading. I use a disposable pipette to sample from the wort. It allows me to take the tiniest of samples.

If I were to use a hydrometer, I would need to take a larger sample and cool it down to 60-70 degrees before I get an accurate reading. This takes time, but it can be done. I have too many other things going on while the wort is boiling then to take a sample, cool it down, and then check the SG.

Since I started using a Refractometer, I have never missed an original gravity. This has helped me create balance in my beers.

How to Use a Refractometer While Fermenting

Since fermenting beer contains alcohol, the reading from the Refractometer will not be accurate. This is where a hydrometer by itself works perfectly. Many people wait until their beer stops bubbling before the use the hydrometer to get the final gravity (FG) reading, but I am nosey and want to know how my yeast are easting as they are going. I still don’t want to lose a half pint every time I check with a hydrometer and I like to check my progress daily (sometimes twice daily). With a complex mathematical formula, it is possible to use a Refractometer even during fermentation.

In a Video, Chris Graham from MoreBeer.com explains how to use a Refractometer during the fermentation process (). The More Beer site also offers a simple Excel Worksheet that takes advantage of that complex mathematical formula so you don’t need to learn math.

All you need to do is take 2-3 drops of fermenting beer and place it on the Refractometer. Take your reading as normal, but then enter it into the Refractometer spreadsheet. As long as you know the starting original gravity, the spreadsheet will do the rest. It is simple and it allows a brewer to know exactly when a brew is done.


A Refractometer has made me a better brewer by allowing me to balance my beers perfectly. Never again will I miss an original or final gravity or wonder how far along my fermentation is. The Refractometer is one of the best investments I have made. You can find them cheap on eBay also. I think mine cost around $24.99USD. It is sturdy and seems like it will last a long time. For me, it was a no brainer.