If it is the entire border, quilting a piano key is a good way to distribute fullness and if you need to take a tuck it is well hidden. If it's really bad, you can quilt the main portion of the quilt, then add an additional layer of batting in the border area.

I've had to do that a couple of times and it turned out fine. Maybe wouldn't pass the judging cause they really really look things over but then maybe not. You go with what you want. When I go to a quilt show, I don't look for flaws rather the overall look of the quilt.

Thanks to you all. I've never had an issue like this before. It's just a quilt for our own bed, but it's so discouraging after making this huge quilt top and doing all that pin basting to discover the two long side borders are wavy. I will try your suggestions as best I can -- I'm pretty new to machine quilting. You're a wonderful group!

Luckily, you discovered this before sandwiching. You have the opportunity to fix it properly now. l advise you to do so...you won't be sorry. Leaving it may cause regret. Next time...sew first border with the pieced part on top ( we usually sew small strips at top & large pieces under...but that causes the problem).Better yet, sew the 3 borders together as a strip first before adding to quilt ( with pieced center on top & border underneath) .

I'm thinking that you may have measured the borders to fit the edges of the quilt. If you measure the borders to fit through the center of the quilt you will work in the excess that may exist in the edges because of stretching and just variances in the piece. This way you solve the problem before you get to the finishing. Works very well for me.

I would not have known and only thought it was suppose to be with the print matching superbly. Would love to see phot of this in its entirety.

I had a wavy border show up after I had it quilted up to that point....uh-oh. What I did was: Undid the border to quilt seam from the middle towards the end. I didn't have to take it all the way off. Then I laid it back against the quilt, determined how much of the border was excess, I had enough to make a seam so I cut the border, removed the excess, seamed it back up and sewed it back on the quilt. There was some trick positioning around the machine but my border looked absolutely normal. I have no explanation as to how/where the excess came from because the quilt ended up being even. Just one of my mysteries of quilting....lol

Have had to take a seam in a couple of quilts I've done with wavey borders.

On a king size bargello I made for son's wedding, the borders where 10" wide and mitered (a free Jenny Beyer pattern)--she had you put all borders together first and then miter. worked fine that way. Also, borders cut from length of grain tend to stretch less---don't do many mitered borders, but any time I do borders that are 3.5" or more I always cut them length of grain--seems to help prevent waves.

Unfortunately, due to the size, I did NOT notice this until after basting the sandwich. Not having a large enough area to see the whole quilt top at once was part of the problem with seeing my error in time.

I always cut mine with the straight of grain, and only the corners are mitered with any bias. I think I measured incorrectly, using the edge of the quilt, rather than the way Sprice menitioned. Thanks to everyone for thinking through so many reasons for this happening to being with, and for thinking of creative ways to correct it!