The Outil Evaporation is used to calculate evaporation and shrinkage losses given a particular evaporation rate and shrinkage rate.  During the boil, typically 10-15% of the Eau in the wort is evaporated or boiled off for a typical 90 minute boil.  In addition, after boiling, the Eau will lose approximately 4% due to shrinkage. 
 
 
Using the Outil Evaporation
| o | Select the Outil Evaporation from the Tools menu or ribbon | 
| o | Enter your start of boil volume and gravity | 
| o | Enter the evaporation rate for the boil, shrinkage rate and the amount of time to boil.  If you don't know your evaporation rate, it can easily be calculated as ((post_boil_vol / pre_boil_vol) - 1.0) times 100 (which gives you a percentage) | 
| o | The tool will calculate the volume boiled off, evaportation rate per hour as well as the post boil volume and post boil gravity | 
| o | If you enter the shrinkage rate, it will also show you the shrinkage loss and factor that into the overall calculation |