Talk:Gravity (alcoholic beverage)

What is this constant
what is this mysterious constant 0.00738? —Preceding unsigned comment added by 216.211.176.54 (talk) 07:53, 9 November 2007 (UTC)

What are the units? Must be mass per volume, but is it kilograms/litres? Or, slugs/hogsheads?

Kentborg 21:01, 16 December 2006 (UTC)kentborg

"expressed as a ratio to the density of water"...i.e., there are no units. 63.250.85.186 18:02, 30 January 2007 (UTC)
 * No units technically, but it's usually marked with a degree sign.76.114.172.199 02:07, 14 September 2007 (UTC)

Range of values
What is the range of values? I mean is a 1010 much worse than a 1050? How high or low do they tend to go? I think something in the article giving some indication of what is the range of values?--Gangster Octopus 20:31, 11 May 2007 (UTC)


 * A few points: 1) Pure water has a specific gravity (SG) of 1.000. This is because it has no solute in it (in this case, no sugar). 2) There is difference between "original SG" and "final SG", which is time. Without qualification, SG generally refers to final gravity. 3) A "better" or "worse" SG is totally dependent on what type of beverage is being made. Wine has a higher original SG because it has more sugar when fermentation start. This results in a higher alcohol content. Beer has a lower SG. A hydrometer made for brewing almost always has range indicator that says (from bottom to top) "start wine", "start beer", "bottle beer", "bottle wine". The more the hydrometer sticks out above the surface of the liquid, the more sugar there is, and hence the higher the density/SG of the liquid is. The exact ranges can be found in a book on brewing (which I don't have available to me at the moment). 4) Each source of sugar has a certain number of "gravity units" (GU) per unit of weight. In the US, it is usually expressed as GU/lb (gravity units per pound). For example, sucrose has a GU/lb of 40. From here, you need to know the volume of the batch (i.e. how much water is in the brewing tank). Example. You mix 10lb. of sucrose into 5 gallons of water. The original gravity is found as follows: 10lb. x 40GU/lb. = 400GU ; 400GU / 5 gal = 80GU/gal ; this means the SG is 1.080 (which is, incidentally, way too high for beer. And sucrose-based beer would be disgusting anyway.). So, the units for specific gravity are either "unitless" (e.g. 1.080) or are expressed as "gravity units per unit volume" (e.g. 80GU/gal.). Fuzzform (talk) 21:25, 17 April 2008 (UTC)

Specific gravity?
Shouldn't the term "specific gravity" be used here? Badagnani 21:48, 20 October 2007 (UTC)


 * No - while the hydrometer reading does measure specific gravity, the phrase "original gravity" is a term of art in brewing to express the specific gravity of the malt and hops mix after it is boiled but before the yeast has been added. Seanibus 18:07, 30 October 2007 (UTC)


 * "Specific gravity" and "specific density" should both be mentioned in this article, as they are the more scientific way of discussing the topic. Homebrewing (or large-scale brewing) is not purely an art; there is a definite science behind it. It began as an art, before anyone knew about yeast, sugar, density, etc., but it has since evolved into a highly systematic process. That isn't to say that you can't treat it purely as an art, but the purposes of Wikipedia, it is necessary to discuss the science as well. A few other points: 1) Hops have a negligible effect on specific gravity. 2) Specific gravity can be measured before boiling as well as after. 3) "Original gravity" and "final gravity" are measurements that involve a time element. Disregarding the time element, "specific gravity" refers to the density of the liquid (the beverage) as determined by the amount of sugar. Since beer and wine are always drunk after fermentation, "specific gravity" (without any time qualification such as "original" or "final") refers to "final gravity". If you go to a pub and the sign says something about the gravity of a beer, you can be sure it is referring to final gravity and not original gravity. Fuzzform (talk) 20:58, 17 April 2008 (UTC)

Image
The metal thing attached to the side of the bucket is a thermometer. The glass thing floating in the liquid, only partially visible, is a hydrometer. It is not the best image. &mdash; goethean &#2384; 18:49, 30 October 2007 (UTC)


 * It was the only "free" one on Flickr. An alternative is for some aficionado to take a photo of their own, or find a better one on Flickr and ask for permission to use it under a free license. Badagnani 20:55, 30 October 2007 (UTC)

Ah, I See you are correct. Thanks for the catch, though the Hydrometer is indeed pitifully small in the shot. Perhaps I will try my own photo on my next batch. Seanibus 00:25, 31 October 2007 (UTC)

Clarification
This article needs to be renamed and completely rewritten. A few major points:
 * "Gravity (beer)" is not a good title, since beer is not the only beverage which is tested for specific gravity. Wine is also tested for specific gravity (with a hydrometer, just as beer is). A better title might perhaps be "Gravity (fermentation)", or "Gravity (brewing)".


 * "Specific gravity" is a term that only confuses the average person. Specific density makes far more sense, considering it is the density of a beverage that is being tested by a hydrometer. The term "specific gravity" comes from the fact that gravity seems to be involved in the flotation of the hydrometer. It is, in fact, not the determining factor for the level of flotation of the hydrometer. The density of the liquid, which is determined by the amount of solute (in this case sugar), is what determines the hydrometer's measurement. In other words: concentration of sugar determines density of liquid; density of liquid determines hydrometer measurement; therefore one can determine how much sugar is in the beer/wine by using a hydrometer. "Residual sugars" is another way of referring to the "specific gravity" of a beer/wine. If a wine contains less sugar, it is said to be "dry". Knowing a beverage's original and final specific gravity (i.e. density) allows one to calculate the percentage of alcohol by volume (%abv).


 * The above information is not found on any of the homebrewing pages (e.g. beermaking, winemaking). There seems to be an unnecessary division between the beermaking and winemaking articles - both beverages are made via the same basic process (i.e. sugars are fermented into alcohol).


 * The overall point: Articles about the underlying principles of homebrewing should not be confined to a discussion of one beverage or another. They should discuss the basic principle, and then its application to the production of each beverage.

Fuzzform (talk) 20:49, 17 April 2008 (UTC)

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Name change
I went ahead and changed the name, since: The "gravity" of an alcoholic beverage is not a term that is confined to the brewing of beer. It applies to all alcoholic beverages. Although consumers only see the term used in relation to beer, brewers (should) know that it refers to the specific density of the beverage, a characteristic measurable in all beverages. Fuzzform (talk) 06:13, 1 October 2008 (UTC)

FG, final gravity
Final Gravity can not be expressed as °P, it should be %mas instead. The Plato scale only applies to wort (= sugars), not to (young)beer as it contains alcohol. WRONG! BEER DENSITY CAN BE MEASURED AS SG OR PLATO IN A BEER THIS PLATO READING IS EXPRESSED AS APPARENT EXRACT (YES I AM YELLING) — Preceding unsigned comment added by 78.148.80.59 (talk) 12:03, 15 June 2016 (UTC)

Plato
There are a couple of references to the formulas and tables in the "Plato" article but the Plato article has been gutted of that material and subsumed into another, "Beer measurement", which contains numerous errors. The Brix article still has the ASBC SG to Plato conversion formula and would be a better place to direct readers at this point. —Preceding unsigned comment added by 98.169.64.210 (talk) 19:05, 7 September 2010 (UTC)

Miracle Yeast
"People commonly refer to the high gravity yeast used to increase the specific gravity of alcoholic beverages as 'Miracle Yeast'." What? Yeast that increases the SG? Something is wrong here... Maybe it refers to high alcohol-tolerant strains, which would decrease it, not increase it? — Preceding unsigned comment added by 213.67.164.75 (talk) 15:54, 24 July 2016 (UTC)