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Missed Original Gravity

Wfu1bunn

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Brewed a imperial stout and the starting gravity was way off.  Should have bee 1120 and came in at about 1045.  I used grains and DME.  I put close to 30 oz of grain in a muslin bag and steeped for 30 minutes.  Could it be that I overstuffed the muslin bag and didn't get enough fermentable sugars from the grain?
 
Wow that is a huge starting gravity. Perhaps you can post the recipe so we can make more informed comments.

Considering you have less than half the sugars in their than you intended perhaps the recipe was for kg of DME and you used lbs instead? You are going to need something like 13lbs of dry extract to hit that. If you are steeping grains you are not going to get much conversion maybe 15%. Even if you had 80% conversion 30oz is not going to make much difference - something like 10 gravity points.
 
Awesome!  Thanks.  The recipe called for 10.5lbs of DME so maybe I read the gravity wrong.  i am a new brewer and this will be a new brewer question, but do you check the original gravity after adding the water to bring the wort to 5 gallons, or before?
 
I call original gravity the gravity of wort that goes into the fermenter. So, that would be after you add water (if needed) to get you at your fermentation volume.

OG - Original gravity is a measure of the fermentable and unfermentable substances in the wort before fermentation. OG gives the brewer an idea of the potential alcoholic strength of the final product. After fermentation when OG is mathematically compared to FG, Final Gravity, the exact alcoholic strength can be determined.
 
There is no way you can ever get to 1.120 with 10.5lbs of dry extract. According to Beersmith you should have a starting gravity of 1.085 with that.

Please note that hydrometers are calibrated at 60F (typically but not always) and any reading taken at any other temp needs to be adjusted (there is a tool for that in Beersmith).

Gravity readings should be taken when the cooled wort is in the fermentor. For extract brewing where you are boiling less than the full 5 gallons this is where you have the opportunity to adjust the O.G. by how much top up (pre-boiled or bottled) water you add. Generally you add water until you get the O.G. you want rather than a fixed volume.

I quickly made up a RIS recipe in Beersmith and it should look something like this (note the ton of hops required due to the super low utilization):

Recipe Specifications
--------------------------
Boil Size: 3.67 gal
Post Boil Volume: 3.38 gal
Batch Size (fermenter): 5.00 gal 
Bottling Volume: 4.60 gal
Estimated OG: 1.120 SG
Estimated Color: 44.2 SRM
Estimated IBU: 67.3 IBUs
Brewhouse Efficiency: 72.00 %
Est Mash Efficiency: 0.0 %
Boil Time: 60 Minutes

Ingredients:
------------
Amt                  Name                                    Type          #        %/IBU       
12.0 oz              Roasted Barley (300.0 SRM)              Grain        1        4.5 %       
8.0 oz                Black (Patent) Malt (500.0 SRM)          Grain        2        3.0 %       
8.0 oz                Chocolate Malt (350.0 SRM)              Grain        3        3.0 %       
15 lbs                Light Dry Extract (8.0 SRM)              Dry Extract  4        89.6 %       
4.00 oz              Admiral [14.75 %] - Boil 60.0 min        Hop          5        53.5 IBUs   
2.00 oz              Goldings, East Kent [6.47 %] - Boil 60.0 Hop          6        11.7 IBUs   
1.00 oz              Goldings, East Kent [6.47 %] - Boil 10.0 Hop          7        2.1 IBUs     
2.0 pkg              Nottingham (Danstar #-) [23.66 ml]      Yeast        8        -           
1.00 tsp              Yeast Nutrient (Primary 3.0 days)        Other        9        -           


Mash Schedule: Single Infusion, Light Body, No Mash Out
Total Grain Weight: 16 lbs 12.0 oz

Also if you want to brew to this gravity you HAVE to have oxygen.

This is an advanced type of recipe and hard to pull off.
 
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