Plain seams fit the bill of ‘keeping it simple.’ This has become a catchphrase in so many areas of life from cooking to entertaining and even sewing. A plain seam is simply the way two pieces of fabric are joined together. The right side of the fabric is placed together with the right side of the other piece of fabric and they are stitched along the seam allowance. Plain seams can be stitched using a straight machine stitch or a very small zigzag stitch if you need some elasticity. They can also be hand-stitched using a backstitch that holds the seam firmly and has some strength.
The basic definition of plain seams is two pieces of fabric right sides together and sewn by hand or machine.
Plain seams can be used on almost any project or fabric type. They can be finished in different ways to suit the fabric type and the style of the garment.
The plain seam has three basic parts, namely the raw edge, the seam allowance, and the stitching line.
How to Sew Plain Seams
- Put your two pieces of fabric with right sides together and the raw edges even.
- Stitch along the seam allowance line. This may be different amounts depending on the item you are sewing. Common seam allowances are 1/4 inch (6mm) for stretch, and 3/8 inch (1cm) for purses, and 1/2 inch (12mm) to 5/8 inch (15mm) for clothing. Always check your sewing instructions as these will vary by designer.
- Neaten the raw edges with one of the finishing options. The edges may be pressed open and finished separately or pressed to one side and finished together.
Plain Seams Sewing Tips
Helpful tips for sewing perfect plain seams:
- SIT CORRECTLY – Start by sitting directly in front of the needle. Align your body so the seam line is running straight in front of you.
- PINS – Before sewing, secure the seam with pins set horizontally from the raw edge. Pins set in this way anchor the seam. If you sew slowly, it is possible to sew over the pins along the seam line.
- WATCH – Keep your eye on the raw edge as you sew along the seam line. The raw edge should follow the seam allowance guide on your machine plate.
- STITCHES – Set your stitch width according to the fabric you are sewing. Suggested sizes are – 2.0mm for lightweight fabrics, 2.5mm – 3mm for medium weight, and 3.0mm – 4.0mm for heavier weight fabrics.
- SPEED – Take it slowly. Although the temptation is to whizz along and get it done, the tension of your seam will be better when you take it easy. Set the speed level on your machine to a moderate speed so you can stick to a sensible speed limit.
- STARTING – Start your seam about ¼ inch (6mm) from the top to avoid the fabric getting sucked into the needle hole and snagged under the needle plate. You will be sewing a backstitch to secure the start of the seam so the gap will be taken care of.
- BE GENTLE – Don’t pull or push the fabric as you sew. The feed dogs, set underneath, guide the fabric through and the needle simply moves up and down to create the stitch.
- FINISHING – Always raise the needle to its highest point to remove the fabric and pull the fabric and threads towards the back of the machine before cutting the threads.
Plain Seams and Seam Allowances
Did you know? The width of a standard tape measure is exactly 5/8” and the correct width of the seam allowance. Hold your standard tape down along the seam allowance to check and see if it is straight. Do this before pinking or serging the seam to neaten the edges.
Finishing Plain Seams
After you have sewn your seam, you will need to finish the raw edges so they do not fray and weaken the seam. The two raw edges will match each other with their right sides together and can be finished in 6 different ways.
Finishing Plain Seams with Pinking Shears
Plain seams can be finished with pinking shears. Cut along the raw edge with pinking shears to prevent the fabric from fraying. Using pinking sears is quick and easy but it is best reserved for fabrics that are tightly woven and don’t fray too much.
The best fabrics for pinked finishes are:
- Lightweight woven fabrics like batiste or voile and sheer fabrics where you don’t want to have too much seam showing or any bulk showing on the right side.
- Items you don’t wash too often and do not fray too much.
- Garments that are hand-washed.
Finishing Plain Seams with Zigzag
Press the seam open and sew along both raw edges with the zigzag stitch. Alternatively, press the seam to the side and finish the edges together.
You may prefer to neaten with the zigzag before you sew the seam. A zigzag is a great way to finish a plain seam if you do not have a serger or you do not want to change the color of the threads on the serger.
Finishing Plain Seams with a Serger
The serger with its cut and sew function leaves a nice clean edge to the fabric. When you are sewing knit fabrics you can stitch and neaten all in one sitting. The raw edges can be finished together or separately.
FURTHER READING: How to Use a Serger
Finishing Plain Seams with Straight Stitch
This finishing technique for plain seams is usually performed on an open seam. Press the seam open, then turn under the edges by only 1/8 inch (3mm). Sew along the raw edges with your straight machine stitch just to prevent the edges from fraying.
Finishing Plain Seams with Overcast
Overcast stitching is a specialized stitch performed by many modern machines. It is similar to the stitching produced by a serger but the edge is not cut as it is sewn. You will need an overcast presser foot. Overcast stitch can also be sewn by hand.
FURTHER READING: Overcast Stitch by Machine or Hand
Finishing Plain Seams with Binding
Plain seams used inside a jacket or skirt without a lining may be finished using a binding to preventing them from fraying. The binding may be used as a feature in the jacket as it could have a decorative finish.
There are two ways to sew binding on a seam:
Hand Sewing Plain Seams
Hand sewing plain seams are going to take a little longer than machine stitching. There may be circumstances when you feel a hand-stitched seam is appropriate or perhaps you are not fortunate enough to have an electrical machine. Preparation is important and it is highly recommended that you use basting before you start to ensure the edges of the seam do not slip as you proceed with hand stitching.
A running stitch is the easiest way to hand stitch plain seams. This simple up and down motion will hold the seam. The smaller the stitch, the stronger your seam will be.
The strongest hand stitch to use is a backstitch. It is helpful to decide on how you plan to finish your seams and to do this first. If your hand-stitched seam is for the lining of a garment then finishing is not necessary.
Double Stitched Plain Seams
A double-stitched plain seam is useful for a seam needing a stronger option. Outdoor clothing or children’s play clothing needs to be hard-wearing. Double-stitched plain seams can be decorative especially if it is sewn in a contrasting color.
Stitch your seam as per the initial instructions. Press the seam open and stitch down either side of the seam line on the right side of the fabric. Use your machine foot as a guide to follow the seam line and make two straight lines. This flattens the seam and gives it added strength.
Plain Seams Around a Curved Edge
Set your seam up as you would for straight plain seams. Mark, pin and baste the seam. Sew very accurately to get the curve exactly right. It often helps when sewing curves to mark the seam line with tailor’s chalk.
At this point, you can trim the seam and press it either open or to one side to see if it is not puckering. If the seam is lying flat, finish it according to your chosen method. If your seam is not lying flat then it might be necessary to clip into the curve slightly to allow more give in the fabric.
When you are happy with the way the seam is lying you can decide if you need to finish the seam or not. The method of finishing a curved seam will depend on the fabric and the position of the curve. If your garment is lined it is not necessary to finish the curved seam. Just be sure it is trimmed and lying flat against the garment. If you have a serger then serging the curved seam is a great option.
Curved plain seams used for sewing facings and sleeves will need to be clipped. Stay stitching around the edge will help to flatten the curved seam.
Plain Seams – In Conclusion
Plain seams are a plain and simple, tried and trusted seam to sew. It has been a means of attaching two pieces of fabric together for centuries and is still the most common seam used.