Acorn Gathering
Float Test for Acorns
Short answer: The acorn float test means placing acorns in water and discarding those that float, since floaters are often hollow, insect-damaged, or underfilled, while sinkers are more likely sound. Dry the sinkers promptly after testing, since the test wets them.
One way to do this step
Fill a wide container with clean water, remove the caps, and drop the acorns in. Floaters usually hide hollow or insect damaged interiors, so lift them out and discard them, then spread the sinkers in a single layer to dry at once, since the test itself wets them. Treat the result as a sorting aid, not a guarantee, and keep inspecting nuts while they dry.
What should you keep in mind?
- Use clean water and a wide container.
- Remove caps before testing so the test reflects the nut.
- Dry sinkers in a single layer with airflow right after the test.
Setting up a fair test
A wide, clean container and clean water give the float test its best chance, because a narrow jar crowds nuts together and makes floating hard to read. Fill the container enough for nuts to move freely, remove caps first so the test reflects the nut itself, and work in small batches rather than pouring a whole harvest in at once. Small batches are easier to lift, sort and dry without confusion.
Reading floaters and sinkers honestly
Floaters usually hide hollow interiors, insect damage or poor filling, because trapped air or missing kernel makes the nut light enough to rise. Lift floaters out and discard them without trying to rescue a batch that has clearly failed the test, and do not let a few attractive looking floaters overrule the result. Sinkers are more likely sound, but sinking is a probability rather than a proof, so further inspection still matters.
Watch for nuts that hover or sink slowly, since they sit between the two clear outcomes and deserve closer inspection. Crack one or two doubtful nuts as a check if you are unsure, and discard the doubtful group if the check confirms poor filling. A test that is read honestly saves drying space for nuts that deserve it.
Drying sinkers straight after testing
The float test wets every nut it sorts, so sinkers must be spread in a single layer with airflow at once, not left in a damp pile while other work continues. A wet pile encourages mould quickly, and a batch that passed the test can still be lost if drying is delayed. Turn the layer occasionally and take out at once any nut showing mould or a soft patch while drying.
Do not seal sinkers in a container until they feel hard and dry throughout, and do not mix a freshly tested batch with a batch that is already dry. Keeping batches separate by test date helps you trace a problem back to its source if mould appears later. Drying is part of the test result, not an afterthought to it.
Limits of the test and later checks
The float test cannot detect every fault, because a nut can sink while still carrying early mould, a small crack or damage that has not yet affected its weight. Treat sinking as permission to dry and inspect further, not as a final verdict on quality. Inspect nuts again while they dry, again before storage and again before preparation, since each stage can reveal a fault the previous stage missed.
If a batch shows many floaters, record that proportion in your notebook along with the tree and date. A high floater rate may reflect a poor year, heavy insect activity or a tree worth comparing with others next season. Notes of that kind turn a single sorting result into useful guidance for future gathering.
Frequently asked questions
Should caps be removed before the float test?
Yes, caps should be removed first so that the test reflects the nut rather than the cap. A cap can trap air, cling to the shell or hold debris, and any of those effects can distort whether a nut floats or sinks. Remove caps during the initial sort, discard them separately and test only the nuts themselves.
Can a floater ever be worth keeping?
A floater is usually hollow, insect damaged or underfilled, so keeping floaters generally wastes drying space and risks mixing poor nuts with good ones. If you are curious about a particular batch, crack a floater open to confirm the fault for learning, but do not dry and store floaters alongside sinkers. The test is most useful when its result is acted on.
How soon after testing must sinkers be dried?
Sinkers should be spread to dry immediately after testing, in a single layer with good airflow, because the test itself leaves them wet. Leaving them in a pile, even for a few hours on a warm day, invites mould that can spread to neighbours. Turn the layer occasionally and remove any nut that softens or shows mould during drying.
What comes next?
Float testing is a sorting aid, not a guarantee, so inspect nuts again while drying.