On Superior beach sand, it will stop the stratifying process about 3/8"-9/16" down, and the lights won't move through it. But your gold is still high in the pan when washing down. That's where you loose it. Once all the garnet is out, then you have a 1/4 pan to go to get to your gold. Then it becomes a matter of proportional force as the gold is as small or smaller as the black sand, but much flatter. The black sand can actually push the gold upward. That is what makes it so dammed hard to pan.
Normally, I pan it down to get the bulk gold out, remove and clean the magnetite, then pan it again to get the remaining scraps. I made a small bucket of those scraps, and had to pan it 9 times to get the gold back out. It's so nasty it does not want to stay in a pan. The only thing worse is trying to pan gold leaf, as it floats over the black sand like mica flakes in a pan. That was so maddening, I threw the pan out!
