Waterproofing a consumer electronic good by urethane/silicone potting

[cm_eng]

Working on a design for a consumer electronic good that must be waterproof to IPX8 (1.5 meters). Relatively simple part: PCB board with a surrounding injection molded clamshell. No connectors or buttons, just an LED or two. Instead of using an oring/gasket to seal out water, I'm considering just sending the housing + board out to be filled/potted with urethane or silicone. There would be additional cost-saving consequences for doing this as well, which I won't dive into here. Does anyone here have experience waterproofing to IPX8 ( or an equivalent MIL or NEMA standard) by means of potting? How well did it turn out? If it worked, any general tips or guidelines? Not finding a lot of information on this out there. Any info helps. Thanks!

Cheers