Sewing Techniques

Seams

A seam is quite simply where two or more layers of fabric are stitched together. There are different types of seaming suitable for different fabrics and projects.

We start the ISEW seam library with two basic seams – Plain and French.

Plain Seams
This is the most commonly used seaming method and is stitched with a straight stitch on woven fabrics and a stretch or zigzag stitch on stretch knit fabrics. The stitch length will vary, depending on the thickness and weight of the fabrics being sewn. Light to medium weight fabrics can be stitched with a small 2.5 mm stitch whilst heavier fabrics will need a slightly longer stitch length.

HANDY HINT: Ensure seams are evenly stitched by using the markings on the throat plate as a guide to distance between needle position and fabric edge. If you require a different distance, position a length of masking tape the distance required from the needle as a guide. Alternatively draw a chalk line down seam line and follow this. Brush away after stitching.

Finish seams by neatening the edges using an overlock or zigzag stitch. On lightweight fabrics the seams can be finished together. On medium to heavyweight fabrics, press seams open and neaten each seam allowance separately.

HANDY HINT: Lightweight cottons can be finished by cutting with pinking shears. Fabrics that do not fray, such as jersey knits, do not need neatening.

Bias seams - Whilst bias fabrics can still be stitched with a straight stitch seam, because the fabric is on the bias it will stretch more. To prevent seams rippling once stitched, hold fabric in front and behind the presser foot, stretching it slightly as you stitch. Once finished and pressed, the stitching will relax into a smooth seam.

HANDY HINT: Add a strip of seam tape, twill or ribbon to the seam line on heavyweight stretch fabrics or bias cut seams such as necklines, shoulder lines etc to prevent the weight of the fabric pulling and stretching the fabric.

French Seams

This seam method encloses the raw edges of the seam allowance so that the reverse of the project looks neat as well. It is ideal for unlined curtains, jackets or any project with transparent fabrics.

1. Pin WRONG sides together and stitch a narrow 10 mm (3/8”) seam. Trim seam allowance to a scant 3 mm (1/8”). Press.
2. Turn through and refold with RIGHT sides together, so seam is on fold. Press again then stitch 6 mm (1/4”) from the fold. Press.

Perfecting Seams

No matter what seaming method is used, there are a few tips that make sure the seams are smoothly stitched without puckers and pulls.

• Before sewing a seam, test stitch using the same combination of fabric and interfacing layers. Try out different stitch lengths – 2.5mm for light to medium weight fabrics, 3mm for medium to heavy and 3.5mm-4mm for heavy and thick fabrics.
• To prevent seams twisting or pulling, stitch all seams in the same direction, ie from bottom to top.
• Avoid threads tangling together at the start of the seam - thread tails can get tangled in the stitching which can pucker fabric or just look unsightly. Prevent this by holding both needle and bobbin thread taut in the left hand as you start to sew. Hold until at least 2.5 cm (1”) has been sewn.
• Prevent fabric being pulled into the feed dogs (into the hole of the needle plate) by starting seam at least 15 mm (5/8”) from the fabric end. Then reverse stitch to end – see below.

HANDY HINT: If fabric still gets pulled into feed dogs at the start of a seam, add some tearaway stabilizer underneath the seam area and/or try a finer needle size.

• Securing seams - Lock stitch or back stitch at start and end of a seam to prevent it from coming undone. To back stitch at the start, begin stitching 15 mm (5/8) from the end, with needle down, reverse stitch to end (holding thread tails as noted above) and then stitch forward over the back stitching. Alternatively, if your machine has a Lock or Fix stitch, use it at beginning and end of seam.
• Feed fabric through smoothly by resting one hand on front of fabric to guide it and the other hand at the side/back to keep it moving.
• Be aware of seam allowances – make sure they remain the same throughout the garment construction (if using a paper pattern, check what the seam allowance is). Generally garments have 15 mm (5/8”) seam allowance, crafts have between 6 – 10 mm (1/4 – 3/8”).

HANDY HINT: When sewing fabric that is difficult to handle such as fleece or lightweight slippery fabric, use a wider than normal seam allowance to give the feed dogs and presser foot more to grip.

• At end of seams, take both threads to reverse of work and then hide thread tails by feeding them between fabric layers within the seam allowance, pull taut and snip off so that they disappear into the seam allowance.
• Neaten or finish all seam allowances to prevent fraying and to reduce bulk in seamed areas. (see Seam Finishes)
• Press all seams before crossing over them with more stitching. Press first from wrong side to embed the stitching and then from right side.

This article has been prepared by Wendy Gardiner