The original directions can be found on page 40 of the Feb/March 2013 edition of Sew-it...today magazine. I have embellished them a bit, to make it a little more clear to someone who might be doing this for the first time.
You'll need 2 yards of 44" wide 100% cotton fabric (do not remove selvages); trim the longest side of the rectangle to 70". (Measure the mattress if you can, to make sure it will fit.) Cut a 9" square from each corner. I folded my fabric in half and cut two corners at once.
Step 1: Press short ends 1/4" under to the wrong side. Stitch.
Step 2: Fold the cut corner's right sides together to form a miter (to make the sheet fitted). Stitch with a 1/4" seam allowance. Repeat for all corners.
|Folding the corner together|
|Corner sewn together|
Step 3: Center a 12" long piece of elastic (I used 1/4" wide elastic) on the corner seam, wrong side up.
Pin down the elastic on top of the seam.
Stretch out the elastic and pin the end down. (I stretched it the wrong way for this picture - you should stretch it to the right instead of the left. Sorry!)
Position the fabric under the sewing machine foot and carefully remove the pin without losing the place where the elastic needs to start. Drop the foot and lower the needle into the elastic & fabric. Sew a couple of stitches, backstitch and then forward again just a couple of stitches, stopping with the needle down. Hold the fabric where you have the elastic pinned at the seam with your left hand, then pull it to stretch the elastic and make it lay flat on the fabric. Grab with your right hand a few inches from the needle, holding that section stretched out, let go with your left hand and use your left hand to gently guide the fabric behind the needle as you sew. Keep doing this until you get to the end (removing the pin in the seam as you get close to it). Backstitch at the end of the elastic, too.
|The stretched elastic will gather the corner.|
Step 4: Press entire sheet under 1/4" to the wrong side, including the places between the elastic, but do not press on top of the elastic itself. It will turn under pretty easily without being pressed.
Stitch a hem all the way around the sheet, beginning in a nice flat area. When you get to the elastic section at a corner, stop with the needle down and stretch the elastic to make the fabric flat, then sew.
And there you have it - a pretty crib sheet for your little one's bed!