Thanks for explaining.
I can see the benefits of the dipper method. However, my brass is way too precious to use as dippers: .44 cases are like hens' teeth!!
I can definitely imagine using this method once I know what load I want to use on a regular basis, so once I've shot and chrono'ed all my new loads that I've been and will be working on and decided on the keepers, then I may well opt for the dipper method.
For now, other members have ground away my resistance!
I've bought some kitchen wiping clothes and I'll make some hard covers with the wipers and a soft, sealing surface. I've got small ratchet straps that I'll use to secure them over my loading trays with the cases in them.
Provided the powder does not cling to the fibres, it should be a solution. Load cases as home and then bullet seat in the icebox... I mean garage.