With this last quilt I decided mitered corners were a must! And they do enhance the 'diamond' effect of the quilt. In order to get my corners to lay flat, I had to look at mitered corners from a fresh perspective. For those of you who sew clothing this will make more sense. This is how I went about it.
Mitered Corners are nothing more than a 'dart'. The quilt borders has an excess of fabric around the circumference not unlike many of my daughters elastic waist pants. To get my daughters pants to fit correctly I have to sew darts in the waistbands of most, if not all of her shorts. This same principle I applied to the borders of my quilt.
The first step is to add extra length to your borders, meaning you have to measure. If you are a lazy quilter like me you typically don't measure the sides of your quilt. I usually hold up my fabric to the quilt and estimate the length I need, the extra I just cut off before applying the side borders. When you Miter corners, sadly you have to measure:(
1. Measure your quilt top and bottom and come up with an average or common measurements for the top and bottom. Then you add the width of the border twice, plus an additional 6 inches. For example if your quilt measures 48 inches across and your border will be 5 inches you add (48 + 5 + 5 + 6 = 64) Therefore your total border length before you sew it on needs to be 64 inches in length. (This is another place where I would run into problems. Somehow I never seemed to have enough extra fabric, probably because I never MEASURED. Curse My impatience!)
2. Now find the center of your first border strip and the center of the edge of your quilt. Mark these with a pin. You can pretty much eyeball the center by folding your border/quilt in half and marking the fold with a pin.
3. Next divide your average width measurement by 2. (In my example average quilt width was 48 inches. When I divide this I get 24 inches.) Measure 24 inches out from center pin on your border, in both left and right directions, and place another pin. These pins will mark your corners. By following this step I have found that this greatly decreases the puckers and waviness of my borders.
3. Pin borders to quilt top and bottom, matching centers and working out to the corners.
4. Sew on borders starting 1/4 inches in from corner. Press your seams out towards your borders.
Please watch where you stop and start your borders. You do not want the border stop or start points to overlap. There should be a small space without stitching right at your corner.
5. Repeat steps 2-4 for side borders. If your quilt is a rectangle your average side length will be a different measurement than your width average. Make sure to measure your quilt in both directions, even if you think, it looks square.
This next part is where it gets a little tricky.
6. Once all borders are sewn on and borders are pressed, lay the quilt out on a flat surface, face down. Your border edges will now overlap.
8. Now swap the border that was on top with the border that was on the bottom and repeat the marking of the border.
9. Now fold quilt on the diagonal so that right sides are facing and border strips face one another. Using your pins as a guide place one pin at a time, starting at inside corner. Push pin in at marked line on top border, through both borders to the other side, directly on the marked line of back border. Be sure that lines match up.
If you are mitering more than one border, it is much easier to get seams to match up if the borders are all sewn together before attaching to quilt.
10. Now stitch line starting at inside corner and working out. I do not back stitch here. (living on the wild side.) I always leave a long tail for easy adjustments. This way if I need to pluck out a few stitches I can without having rip out the entire seam or re-sewing the entire corner. (although some corners scream: SEAM-RIPPER!) When I am sure the corner will lay the way I want, I tie the tails in a square knot, just as if I were making a dart.
11. Press corner and seam open before trimming seam to 1/4 inch.
12. Repeat on remaining sides then....Sit back and enjoy your beautiful corners!