Calculating OG

[The_viking309]

Hello all, I'm completely new to brewing. I started a mead, and I'm having a hard time understanding the whole calculation thing for the original specific gravity. When I used my Brix refractometer, the day of making the mead my Brix was 4, and the SG Wort was 1.017. How do I obtain the OG from these measurements? I'm asking because I just took a new measurement since I just added the first amount of Fermaid O. The reading was 23.1 and 1.087. Do I need a hydrometer at this point?

 

[The Brew Mentor]

Hello,
A refractometer is a good tool to use in the beginning prior to fermentation. It'll give you a quick measure of the sugar content of the liquid prior to fermentation. This will be accurate if the liquid is homogenized. If not, the sugar will settle to the bottom and you'll be reading the mainly water that you drew off the top. I think this may be the case in the above example.
After the fermentation begins and you begin to have alcohol present, the refractometer is significantly less accurate, even if making suggested corrections.
This is where a Hydrometer is a better tool to see where you're at in fermentation and also when you're finished.
The difference in the starting gravity and the ending gravity will calculate out to tell you the ABV you've produced.
The calculator on the site here will make short work of that.
Good Luck and welcome,
Brian

 

[MaxStout]

Welcome to the forum!

If you have a hydrometer, take a reading with that, in addition to the refractometer. The two measurements should be very close. Be sure to stir the must thoroughly before taking a sample. As @The Brew Mentor pointed out, it's likely lack of mixing that made your SG go from 4 to 23 Brix.

 

[The_viking309]

Welcome to the forum!

If you have a hydrometer, take a reading with that, in addition to the refractometer. The two measurements should be very close. Be sure to stir the must thoroughly before taking a sample. As @The Brew Mentor pointed out, it's likely lack of mixing that made your SG go from 4 to 23 Brix.

I appreciate the advance @The Brew Mentor and @MaxStout . I'll have to buy a hydrometer. I did mix the honey and water together before putting everything else in, and let it sit a little while before I took the measurements. Hopefully I'll be able to get the hydrometer soon and get a better measurement.

 

[Minbari]

I appreciate the advance @The Brew Mentor and @MaxStout . I'll have to buy a hydrometer. I did mix the honey and water together before putting everything else in, and let it sit a little while before I took the measurements. Hopefully I'll be able to get the hydrometer soon and get a better measurement.

It will still have to be stirred though. If all the sugar is on the bottom, it won't read correctly.

Pre fermentation, a refractometer works just as good, imho. It's allot faster and uses a drop instead of 50+ml. Post ferm, use a hydrometer

 

[Donoroto]

OG is original gravity, probably 1.087 as you noted. After fermentation FG is final gravity, and since alcohol is present your refractometer will read high, so a hydrometer is needed. The difference between the OG and FG will let you calculate alcohol by volume (abv) as a percentage.

If you don't care about the abv, you don't really need a hydrometer. But they are useful and inexpensive.

Once your mead wort is sanitized (boiled? Dunno. Never made mead) you should cool it and put in the yeast as soon as possible, to prevent something else from processing the sugars (like bacteria).

 

[MaxStout]

Another reason to have a hydrometer is to confirm that fermentation is complete. You take a couple gravity readings a day or two apart. If they are the same, it's an indication that the yeast is done.

You can use a refractometer, but the alcohol content will distort the reading. (Alcohol has a different index of refraction than water.) There are formulas to correct for this, which will give you an approximation. However, a refractometer can also be used to check for changes in gravity, to see if fermentation is done.

 

[Minbari]

Another reason to have a hydrometer is to confirm that fermentation is complete. You take a couple gravity readings a day or two apart. If they are the same, it's an indication that the yeast is done.

You can use a refractometer, but the alcohol content will distort the reading. (Alcohol has a different index of refraction than water.) There are formulas to correct for this, which will give you an approximation. However, a refractometer can also be used to check for changes in gravity, to see if fermentation is done.

yup, done this for years. in fact I only recently bought a hydrometer after brewing for 7 years, lol