Final batch ABV
If you measure the finished strength of a batch rather than working it out from gravity, you can record that measurement as an ABV batch reading and mark it as the batch's Final batch ABV. Breww can then use it as the ABV the batch's duty is calculated from.
This works in the same way as marking a gravity reading as the original or final gravity, and it's useful wherever the gravity sums don't tell the whole story, such as blended ciders, fortified or sweetened drinks, or anywhere you have a lab ABV you trust more.
Adding ABV to a reading form
ABV is one of Breww's built-in readings, but it isn't on your forms to start with. Add it to a batch reading form at Settings -> Production settings -> Batch reading forms first. See Batch reading forms.
Marking a reading as the final ABV
When a form includes ABV, the reading form shows a Final batch ABV checkbox beside the ABV field. Enter the ABV, enable the checkbox and save.
You can also mark or unmark an existing reading by editing it from the batch's Analysis tab, and the same tag is available through Breww's API.
A batch can only have one final ABV. To move the tag to a different reading, clear it from the reading that currently has it first.
Using the final ABV for duty
Breww works out each batch's duty ABV from its ABV calculation method. Choosing Final ABV entered as a batch reading makes Breww use the tagged reading.
The default is set per drink type at Beer duty/Alcohol duty -> Annual estimate & settings, and can be overridden on an individual batch.
While a batch is using this method:
- It can't be packaged until an ABV reading has been marked as the final batch ABV.
- If your duty regime works in degrees Plato, the batch also needs a gravity reading marked as its original gravity, because that's where the Plato figure comes from.
While any drink type is set to this method, ABV has to stay on your default batch reading form, so the reading can always be recorded. Breww won't let you remove it, or make a form without it your default, until you change the method. The same applies to Gravity if your duty regime works in degrees Plato.
The setting is only a default. It's copied onto each batch as the batch is created, so changing it doesn't alter batches that already exist. See Duty settings.
Seeing it on the batch
The ABV card on the batch shows the ABV being used for duty and the method it came from, the ABV calculated from the batch's gravity readings, and the final batch ABV. A Used for duty badge marks whichever one the batch's method actually uses.
The Analysis tab also plots an ABV chart, with the ABV calculated from gravity readings, any ABV readings you've entered, and a star marking the final batch ABV.
When a final ABV is for reference only
You can record a final ABV on any batch, whatever its ABV calculation method. If the batch isn't using the Final ABV entered as a batch reading method, the reading is stored for your records but isn't used for duty, and Breww makes that clear rather than letting you assume otherwise.
The readings table on the Analysis tab shows a warning badge beside the tagged reading in the same situation, with the reason in its tooltip.
Protecting a tagged reading
Once a batch has been racked, a tag that feeds its duty can't be cleared, moved to another reading or deleted. This covers the final batch ABV under this method, and the original and final gravity under Automatically calculated from batch gravity readings. Other tags on the batch stay editable.
Once a batch has duty entries against it, only users with the Brewery admin permission can change the tagged value itself, which matches how original and final gravity have always behaved.