# Gravity

This may be a stupid question, but I was looking through the FAQs and saw a lot of reference to the “gravity” of a brew. My question, as I did not see an answer in the FAQs is, what is gravity and how do you test it without possibly contaminating your brew?

Use a sanitized turkey baster, or something similar, to take a sample to fill a hydrometer flask. Put your hydrometer into the flask and read the line where the wort comes up to. Do not return the sample to the fermenter. Drink it or (horrors!) pour it out.

Where would I get a hydrometer flask, or is there something I could use as a makeshift one?

Oh, and what line am I looking for?

Try this. There is also a video how to on the right side.

http://www.northernbrewer.com/shop/ferm ... t-jar.html

[quote=“dsiets”]Try this. There is also a video how to on the right side.

http://www.northernbrewer.com/shop/ferm ... t-jar.html[/quote]

Ok, I watched the video and am trying to process what they were talking about. Is the gravity the amount of sugar in the brew or the amount of alcohol? And why is it called “gravity”?

http://www.howtobrew.com/appendices/appendixA.html

[quote=“KnoticalBrewer”][quote=“dsiets”]Try this. There is also a video how to on the right side.

http://www.northernbrewer.com/shop/ferm ... t-jar.html[/quote]

Ok, I watched the video and am trying to process what they were talking about. Is the gravity the amount of sugar in the brew or the amount of alcohol? And why is it called “gravity”?[/quote]

It is called “specific gravity” formally. It works because sugar dissolved in water raises the specific gravity of the water. The more sugar, the higher the gravity. There are lines on the hydrometer scale corresponding to gravity numbers. You put the hydrometer in the flask of wort and read the number of the line that the liquid is at.

I find it interesting that something that is completely unrelated to a certain subject will actually provide quite a bit of insight on it.

What do I mean? Well, I just started a new job with an oil company and during the training of said job we went through oil-field science. How is this important? Well, this actually requires a little bit of background about myself. You see, in high school (which was over 20 years ago) I never took chemistry or physics, as I was not all that ambitious. Anyway, had I actually taken those courses I may have actually been exposed to the basis for understanding this topic - gravity.

What I learned in the oil-field science portion of training is that water at about 60 degrees Fahrenheit weighs roughly 8.33 pounds. This is where the basis of gravity comes from. Based on this water has a gravity of 1. All other liquids are compared to this and will either be heavier or lighter than water. Most liquids are lighter than water, even oil.

But when it comes to brewing beer that gravity is not only referring to the weight of it compared to water, but specifically how much sugar is in it. And the reason you take a hydrometer reading before and after fermentation is to find out how much alcohol is in it. You see when beer ferments it turns the sugar into alcohol and at the same time reduces the gravity of the liquid. Thus the difference in the readings will tell you how much alcohol is in your beer, which is translated into percentage by volume.

I hope this little bit of info helps other newbies, as I know even after I had read some of the tips and tricks in various places this basic information was still omitted and pretty much left me a bit confused.

Cheers!