Test for O.G. – Original Gravity
Test for Original Gravity—————————————
Check the specific gravity, AKA the O.G. original gravity. Adjust specific gravity based on the temperature of the mash. Target 1.090 This is your reading before any fermentation producing the alcohol. You will take another specific gravity after fermentation to see what your ABV is before distilling. Note: a specific gravity reading above 1.110 will stress most yeasts and produce foul oils.
And as soon as you get to 80F you need to aerate and pitch your yeast into the mash so it will dominate and start acting right away. 89F and below is OK to pitch yeast if the temperature is dropping. At or above 90F the yeast will get stressed and produce non-desirable oils and gasses.
Specific Gravity Test
Calculate the specific gravity after fermentation. Best is 1.090 or better – a potential 12% ABV in the mash or wash. Yeast will start to die off around 15% ABV in a wash. However there are alcohol resistant yeasts that can still function until around 19% ABV.
With a calculated gravity, OG minus FG (original gravity minus final gravity) of 1.100 to 1.090 you will get a normal distillation where the heads will come out at around 60% ABV. The hearts will be vary from 50% to 40% ABV. When 35% ABV starts coming out the tails will start to appear and the taste will be unpleasant.
Hydrometer Chart
| Specific Gravity (SG) | Potential Alcohol (PA) % by Volume | Amount of Sugar Per Gallon |
| 1.010 | 0.9 | 0 lbs. 2 oz. |
| 1.015 | 1.6 | 0 lbs. 4 oz. |
| 1.020 | 2.3 | 0 lbs. 7 oz. |
| 1.025 | 3.0 | 0 lbs. 9 oz. |
| 1.030 | 3.7 | 0 lbs. 12 oz. |
| 1.035 | 4.4 | 0 lbs. 15 oz. |
| 1.040 | 5.1 | 1 lb. 1 oz. |
| 1.045 | 5.8 | 1 lb. 3 oz. |
| 1.050 | 6.5 | 1 lb. 5 oz. |
| 1.055 | 7.2 | 1 lb. 7 oz. |
| 1.060 | 7.8 | 1 lb. 9 oz. |
| 1.065 | 8.6 | 1 lb. 11 oz. |
| 1.070 | 9.2 | 1 lb. 13 oz. |
| 1.075 | 9.9 | 1 lb. 15 oz. |
| 1.080 | 10.6 | 2 lbs. 1 oz. |
| 1.085 | 11.3 | 2 lbs. 4 oz. |
| 1.090 | 12.0 | 2 lbs. 6 oz. |
| 1.095 | 12.7 | 2 lbs. 8 oz. |
| 1.100 | 13.4 | 2 lbs. 10 oz. |
| 1.105 | 14.1 | 2 lbs. 12 oz. |
| 1.110 | 14.9 | 2 lbs. 14 oz. |
| 1.115 | 15.6 | 3 lbs. 0 oz. |
| 1.120 | 16.3 | 3 lbs. 2 oz. |
| 1.125 | 17.0 | 3 lbs. 4 oz. |
| 1.130 | 17.7 | 3 lbs. 6 oz. |
Temperature Correction Chart
| Temperature of Sample (degrees F) | Specific Gravity (SG) Reading Correction |
| 50 | -.0005 |
| 60 | .000 |
| 70 | +.001 |
| 77 | +.002 |
| 84 | +.003 |
| 95 | +.005 |
| 105 | +.007 |
