help with SG reading

[Cadbury]

G'day men,
Just did an all grain pilsner and the pre-boil SG was supposed to be 1.043, but it was 1.052. What does this mean in terms of my effeciency? Am I going to be able to drink it? I still get a bit confused with SG readings. Can someone please explain how they work and in an easy to understand way? I thank you in advance.
Cadbury

[warra48]

1.052 for an OG is almost identical to the OG of 1.053 of an all grain BoPils I'm lagering at present. It will be very drinkable, BeerSmith predicts 5.6% ABV for my brew using a WY2001 yeast starter.

Efficiency is dependent not just on the OG, but also the weight of grains used, and the quantity of wort collected. It's really quite easy to work out. If you have a program such as BeerSmith, it will calculate it for you if you put in your OG and FG.

I did a post on efficiency only recently. Here it is again:

Mash Efficiency

Brew maths is quite simple.

How it works is all malts and adjuncts etc give a different gravity.
The specs are all written as H.W.E which is hot water extract with sugar being the highest at 386 so everything else is given as a % of that. ie, pale malt is around 81% which gives you around 309. this is the total gravity you can get with 1 kilo in 1 litre but it is near impossible to get this, this is 100% efficiency.
the same goes for american calcs but its in P.P.G which is the gravity of 1 pound in 1 gallon. The same specs are used ie. 81% for pale malt gives you 37 points of gravity.

I'd strongly recommend you spend about $25 and buy BeerSmith. It's invaluable in AG brewing, in spite of some well documented foibles in the program.

So a simple example to work out total potential for 5 kg of pale malt in 23 litres is
5 x 309 / 23 = 67 (1.067)

Now to work out your efficiency you divide the gravity you got with this brew. Say you got 1.050 so 50/67 =.74 you got 74% efficiency.
Then next time when you do the calc. 5 x 309 /23 =you simply times this by .74 .
This gives you your expected gravity,

For your first batches i would stick to using 65 to 75%.
So do the 5 x 309/ 23 = 67.
then times 67 by .65 = 43(1.043)

P.S. the H.W.E. numbers are often on the maltsters website. Other malts like crystal malt are around 75% some malts can be lower and some higher.
To get the number times 386 by the percent as a decimal point ie pale malt at 81% gives you 386 x .81 =312

Some indicitive examples, noting they vary from batch batch and malster to maltser to some degree.:
Ale -------81% X 386 = 312
Pilsner----------------81%
Munich----80%
Melanoiden--------- -80%
Caramalt pils---------79%
Crystal---------------- 75%

Say the HWE is 308 litre degrees per kilogram for a malt.
That means 5kg in 20L will give you : (308 x 5)/20 = 77. i.e. 1.077 SG at 100% efficiency. Multiply that by your efficiency (eg. 75%) gives you 77 x 0.75 = 57.75 or close enough to 1.058.

Hope that helps. Let us know if you have further questions.

[Cadbury]

I did the recipe using beersmith. Why does it say pre-boil SG 1.043 and then say Original Gravity 1.055. My pre-boil was 1.052 and I don't know what my OG is yet because I haven't put it in the fermenter yet. Beersmith gives me all these wonderful figures but it doesn't tell me what they mean and what to do if I don't get them!
Cadbury

[warra48]

I presume your original gravity reading has been temperature adjusted? Use the Hydrometer Adjust tool in the left task bar.

Apart from that, if your pre-boil SG is 1.043, you will boil off a certain volume, and concentrate your wort to a higher SG. Thus: say 31 litres pre-boil at 1.043, allow 6 litres evaporation, leaving 25 litres at 1.053 !
BeerSmith calculates this for you, based on your equipment and settings you have entered.

If you go to your recipe, click on the box "Details" in the line where it says Equipment. You can then enter the details of your desired settings.
Alternatively, if you click the box which says "Choose", and then click "New" at the bottom of the pop up box, you can design a totally new entry based on your specific equipment, give it a name, and then choose it for your recipe. You might need to edit it a few times, until it predicts results in line with your actual outcomes.

The BeerSmith Help Page may be useful as well. Click on the Arrow/Question mark logo in the task bar, then click on any field you are not sure of, and the Help Page will open.

BeerSmith OG and FG figures are only a prediction, based on your selected Brewhouse Efficiency %, the malt bill, the avarage attenuation for the yeast you have entered, and your equipment settings. My actual results are never exactly as predicted by BeerSmith, although I get close.

Hope you can figure it out. I find BeerSmith a really useful tool, but it did take me a while to get my head around all the functions it has.
There is a post, if I recall correctly, about setting up BeerSmith, as it does have some foibles which need to be understood and allowed for.

Edit: Found it, here's the link: viewtopic.php?f=13&t=9007

[Cadbury]

Thanks very much for your time and patience. I don't know what I would do without the people with all the knowledge and are willing to share it.
Cadbury

[billybushcook]

Specific Gravity (SG) is the density of a fluid compared to water.
Mass per unit volume
in metric, this is Kg/cubic meter (standard SI units)
ie, pure, fresh water = 1Kg/Liter = 1Ton/cubic meter

So if SG is a comparison to water. 1.000 would have the same density as fresh water.
any soluble solids added to the solution will change its density (mass per cubic meter)
Add salt to water & its SG becomes more like 1.1000 because salt is hevier than water for the same volume(1.1Kg/Liter or 1100Kg per cubic meter)

Same goes when you add sugars to the solution as long as they are disolved into the solution.

when solids which have a density lighter than water are added, it can lower the SG below 1.000 but they must be in solution or they will float because their density is less than water, (density less than 1000Kg per cubic meter is boyant because it displaces more than its weights worth of water)

The way a hydrometer works is that the more dense a solution the more boyant the hydrometer hense it will sit higher in the solution.

Hope this helps with getting a feel for what SG really is.

Mick