There are no gaskets on the lid. They did tests and determined gaskets didn’t make much difference. I’m willing to bet that’s because the lid is so lightweight and there’s nothing really pushing against the gasket to create a seal.
Original Form 1 rinse buckets had great clip-on lids with silicone[?] gaskets that created a perfect seal. Unfortunately the gaskets would degrade over time after lots of exposure to alcohol. The latest Form 2 manual rinse buckets have lid gaskets which I think seal decently when using the clip-on lids but don’t do much when you use the convenient, flip-up lids integrated into the station. They help a bit, but are not as effective. The Form Wash abandoned gaskets altogether. Some users (including myself) do find it evaporates quicker than expected - you have to top it off regularly.
Hope that answers your question!