So, you've carefully cut, sewn, pressed and prayed to the gods during the construction and birthing of your newest creation. Add the batting, backing and leanest of quilting, and....phooey! The outer border of this modest of sizes (29 1/2" square) quilt waves more than the court princess on the homecoming parade float.
No worries--you can still hold your head high. View the wavy outer border in the first photo, then the visibly straighter, flatter outer edge of the second photo. Start your straightening operation in much the same way as you would preparing for binding by determining the desired measurement for the outer edge. You can determine your desired outer measurement by using a cardboard cutting board, cutting mat and/or square, even the lines in tile flooring can be drafted into service by aligning quilt edges with a straight edge. Measure the narrowest points, taking an average if necessary. Most of my wall quilt pictured settled in at 29"--I fluffed the extra around the edge inward so the corners settled squarely. Quilting had reduced the measurment from the original 29 1/2". You can lay your tape measure over the top of the excess to read your measurement and over the center of the quilt to do the same.
You've determined your average and decided on a measurement for your outer border length on top/bottom and for the sides--now what? Obviously, you want to shrink in the excess on the outer edge to conform to these modified measurements before you apply binding and forever preserve the excess length into a wavy finished edge. On the quilt pictured, I used a piece of rayon seam tape (and twill tape works well) cut to the finished length desired--in this case 29". I pinned the tape to the back side, ends of tape first (aligned at each corner), then just kind of tamped the excess border under the stable tape evenly from edge to edge. For larger quilts, you may want to mark the midpoint of each before pinning, or quarter marks if the length calls for more register marks. (Note that bias tape stretches and will not work as a stabilizer). Pin tape just outside the 1/4" seam line (within the seam allowance) to ensure stitching does not show on quilt face. Machine baste tape the entire length of the seam line. Once you have eased the excess border under the tape, you are ready to apply bindings.
Do you own any fabrics that you just love....so much so that you can't bear to cut them up into small pieces? They're either too beautiful to sacrifice, or just too perfect in their original, uncut state--perhaps a large print that loses its character if not used in its entirety. I have several I've collected over the years, both commercially-printed yardage and some hand dyed, one-of-a-kind fabrics. What to do? Well, don't cut them! The Modern Quilting trend gives us even more permissions to deviate from the traditional. Like many folks, I purchase fabrics I love on the spot and decide later what they will be used for. The lap quilt (36" x 48") at left uses salmon-colored Moda Marble on the borders with Alexander Henry's La-Ti-Dot in the central medallion in this trendy, fast and easy quilt--use as lap quilt or wall art. The fancy-cut binding that mimics a scallop-edge border is cut from the same Alexander Henry print. 
