I've just taken up 8x10 after years of doing 4x5 and am amazed at some of the differences. Such as - how do you get the large negatives to sink in the presoak bath?
With 4x5, I would remove the film from the holder, drop it into the presoak, and give it the slightest push with my little finger. It would sink right away and I could quickly add another piece of film.
With the 8x10, I drop in the film, give the the push, and it stays on top. The surface tension keeps it floating. If I were to add a second film before the first sinks, they would stick together.
So, what's the consensus of how to get the film to sink. Just wait - rock the tray - push down harder with more fingers?