Sewing a crotch seam in a pair of pants or shorts isn’t hard, but this sewing technique can strike fear in the hearts of many beginning seamstresses. Some of the commercial sewing patterns have instructions that are confusing, which is unfortunate, because sewing the crotch seam in a pair of pants is really quite easy.
One of the simplest types of pants to sew is a pair of pants with an elastic waist. This type of pant may be more casual than a pair of pants with a zipper and a waistband. (Sewing the crotch seam is the same for both types of pants, but if you have a zipper closure, you would need to start sewing at a different place on the crotch in order to leave room for the zipper to be inserted.)
Make sure that you have pre-treated your fashion fabric before sewing the pants. If you are making a casual pair of pants or shorts, you may choose to use 100% cotton fabric, which needs to be pre-washed to accommodate any shrinkage that might occur. Press the fabric well before pinning and cutting out the pattern.
A simple pants pattern consists of a back leg and a front leg pattern piece. Cut these out of the fashion fabric, press well, and then decide which type of seam finish you would like to use. If you have a serger, you may decide to serge the raw edges of the pieces prior to sewing construction. With this method, you will press the seams open after you have sewn them together. You could also choose to sew the seams, serge them, cutting off some of the seam allowance, and press the seams to one side. The advantage to the latter method is that it is easier when finishing the raw edges of the crotch seam. You could simply serge the seams, but that creates the need to serge the seam very accurately, and if you have serged and finished a seam, but have made a mistake, it is not correctable, which is why it is often better to sew the seam on a conventional sewing machine first, and then serge finish the seam.
When sewing a casual pair of pants, sew the inner leg seams together first by placing a front leg to a back leg, making sure that the right sides of the fabric are together. After sewing these inner leg seams, press them flat, as stitched first, and then press the seam open over a seam roll, or to the side, if you have serge finished. Then sew the outer leg seams together in the same manner. You will now have two separate pant legs. Turn one pant leg right side out, with the right side of the the fabric facing you. The other pant leg will remain inside out, with the wrong side of the fabric facing you. Insert the right side out pant leg into the wrong side out pant leg, matching the inner leg seam, and making sure that the fabric is right side together. This is the crotch seam, and it forms a “U” shape. Pin around this “U” shape, and sew the seam. Press the seam open (as far as you can) or to the side, depending on the type of seam finish that you have used. All that remains to be sewn is the waistline casing and the hem of each pant leg.
Sewing a crotch seam in a pair of pants is really quite easy, and using this method ensures that seamstress will be successful in creating a nice pair of pants.
