It doesn't seem to bother the Black Watch and they wear the Red Hackle in all weathers.
This was why I asked if it could be my hackle, and how large the loops should be--what's proper, or average.

Because, quality varies on these things as with all else. I think a few sites offer (or claim to) hackles made to MoD specs.

In the case of hackles, it's a difference between US $6 and $12, I believe-unless there's snazzier ones out there I'm unaware of. If $12 makes it colorfast then well worth it to the cost of the rest of your uniform.

I wore a black one in Portland, Oregon rain though, and never noticed such problems. It will make me err for quality though so I don't run into the same issue of bleeding or fading in the sun.