How many hours will it take me to sand floorboards in standard size room?

[Dave Liquorice]

A film wouldn't clog the duster in two or three non overlapping wipes requiring it to be shaken out or rinsed. A layer would.

[Mary Fisher]

I suggest that's a subjective definition :-)

Mary

[Guy King]

The message from "Mary Fisher" contains these words:

If you can roll it up like felt - it's a layer.

[Dave Liquorice]

But it would make an excellent subject for a post grad thesis. Like "Do you get wetter if you walk or run in the rain?"