Blend Fields in fcp

i am trying to create a color wipe across a stylized clip. i saw this technic used on an xgames promo.
what happens is as the clip show a biker racing from left to right the color blue wipes and the the color red. i thought the effect was simply a blue 30% opacity rectangle that motions across the screenbut it is not. a friend who was seeing it with me said it was a keyed blend field. i cant find out much about blend fields in the fcp manual.
however i have seen blend fields in motion but was unsure that i could key them in such a deliberate mannor.

can blend fields be manipulated in fcp?

""" What you do with what you have, is more important than what you could do, with what you don't have."

> > > Knowledge + Action = Wisdom - J. Corbett 1992 """"

Call me foolish, but I think you're getting ignored because no one knows what you mean by a "blend field". The term isn't in the FCP manual or part of polite conversation amongst FCP cutters...

When I Googled the term to see if it was just me, I got three references to Alpaca socks and your post here. Perhaps a better description would get better results.

The concept sounds interesting... so do the socks!

ok,
the only place i have found any reference to blend fields is in motion, i.e. stencil alpha is a type of blend field. it can be found by right clicking any object in motion.

the way i was seeing it used was this:
say you have a 15sec clip of someone running from rite to left pass a camera. pretty simple footage.
what i am trying to achieve is while that person is running across that screen in color i want to make one of the colors become a color burn that wipes across the screen over 6sec. so if the person has on red shoes, red hat and red gloves this color burn if it were done vertically from top to bottom would cause the hat to glow/burn the hat and as the burn moved downed the hat would go back to norm saturation as the glove began to burn and as the glove began to come out of its burn the shoes would begin into their burn and then go back to norm.

like a color wipe sorta.

does that help at all.

""" What you do with what you have, is more important than what you could do, with what you don't have."

> > > Knowledge + Action = Wisdom - J. Corbett 1992 """"

You could do that pretty easily with a duplicated clip with the colour style you wanted on the second layer. Then just keyframe a moving crop top to bottom over the 6 seconds.