Tim, there was a reply to one of my wrapping dry hay posts earlier where someone made a good case for black for open ended dry bales.  My local supplier only carries white so thats what I use.

I'm not sure color is as important as film strength/stretchability and cling. You want the wraps to seal tightly to themselves to seal out rain and snow from the top and soil moisture from below. Thats usually the point of this type wrapping.  And you will need the 30" for the roundabout if thats what you are using.

You also want a film that you can stretch without it breaking in the middle of wrapping a bale. That is a pain.

A stronger clingy wrap lets you seal with fewer turns around the bale. This is another case where the cheapest film may end up being the most expensive or vice versa. My experience.

Jim