How you know it is done
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The two things to establish
That fermentation has ceased, and that the product is acid enough. They usually arrive together and they are not the same observation, so check both.
- Activity has stopped. No more gas, and the brine has gone quiet. Bubbling that continues is a ferment still running, whatever the calendar says.
- The acidity is right. This is a measurement, with a calibrated meter, not a taste.
Why the date is a plan rather than a test
The published three to four weeks assumes the published temperature. At 55 to 65F the same ferment takes five to six weeks, so a date set from the recipe is wrong by two weeks in a cool room, and wrong in the dangerous direction in a warm one. Finishing a batch early because the calendar said so is how an under-fermented product reaches a jar.
The reverse error costs less but still costs. A ferment left well past finished is not unsafe for having sat, but it is a vessel you could have emptied and refilled inside a short season.
What happens next is a separate decision
A finished ferment is a live product. It can go to refrigeration as it is, or it can be processed for shelf stability, and those are different products with different shelf lives, different labels and different logistics. That decision belongs to its own page and it is worth making before the first batch finishes, because a live product you had not planned to refrigerate is a problem on the day it is ready.
If the plan is to sell it shelf stable, the acidity measurement above is not optional and it is not a formality. It is the number the whole regulatory position rests on.
Measure it on a settled jar, not a warm vessel
Acidity is measured once the product has equalized, which is the point of the equilibrium pH page. Reading a meter in a vessel that is still active, or in brine that has not come to room temperature, gives a number that was true of that moment and of nothing else. If the reading is going to be the basis of a shelf-stable claim, it has to be taken under the conditions the claim describes.
Calibrate before the reading rather than at the start of the season. A meter drifts, buffers age, and the one measurement in this craft that everything else rests on is not the place to assume an instrument is still right because it was in July.