Yes, most that sink will be filled and viable, but that doesn't necessarily mean the 'floaters' won't germinate, the floast test isn't completely reliable for determining viable seed.

Thanks for the info. That's what I thought, most "floaters" are empty or will have difficulty germinating.

I usually sow only the seeds which sink so the few that float after 24 or 48 hours are most likely not viable and I discard them.

Thanks again.

The fact is the float test is not a reliable way to tell if ALL seeds are viable. In other words you could be throwing away a lot of good seeds. Al

In my case, if I have lots of seed to work with, like native plants from the yard, then I will be a bit more selective with my seeds and typically only use seeds that sink after a good soak.

If I work with purchased seeds and have only a very limited supply, then I will use most seeds whether they float or sink.