How to handle your dice if they roll with a bias

I have purchased several sets of dice from different online retailers. I did some salt-float tests on them recently and I’m concerned a good amount of my d20s are favoring a specific corner (all 3 like the 6/9 intersection for some reason).

I’m in a friendly campaign where we’re not taking ourselves too seriously so "weighted dice" aren’t necessarily a problem (especially with such low-rolling dice), but I still want to level the playing field of my dice.

I’m thinking of using a high-walled rolling tray and some textured padding, like a towel, so the bouncing from the walls and the friction from the towel would prevent the dice from "snapping" into desired positions.

Would you say that’s a good way to deal with them? What would you do, besides getting rid of them?