Knowing the yield, exactly how much oil you have in the oil glass after an extraction, is key to the correct dosage. When you want to use your extract for example for edibles, oral drops, or for inhalation, you want to know exactly how much oil is in each dose.
A simple and precise way to know the exact yield is by measuring the tare weight, and later deduct it from the gross weight.
Tare weight is the weight of the oil-glass and the glass-beads that goes in the glass to prevent steam-boiling.
Gross weight (in this context) is the weight of the oil-glass, glass-beads, and the extract, after the extraction is done.
Since you want to know the weight of your extract down to a 0,1-gram precision or better, the measurements need to be precise, preferably with 2-3 digits, e.g. 25,420 grams.
Here are the steps you want to perform to get a precise measurement of the weight of your extract:
1) Measure and make a note of the tare weight (glass+glass beads) before inserting the oil glass in Merlin400
2) When the extraction is done, measure the gross weight (the oil glass, with glass beads and the extract)
3) Extract the tare weight from the gross weight, and you have the weight of your extracted oil!