How to pin fabric correctly

Pin fabric at right angles to the seam line, with the heads sticking out past the raw edge so you can pull each pin out with your right hand as the foot reaches it. Match and pin the two ends and every notch first, then fill in between: a pin every 5–8 cm (2–3 in) on a straight seam, every 2–3 cm (about 1 in) on curves and slippery fabrics. Never sew over a pin; the needle either bends it or breaks on it.

Why does pinning matter?

Two layers of fabric do not stay aligned on their own. The presser foot pushes the top layer slightly backward while the feed dogs pull the bottom layer forward, so an unpinned seam ends with the top layer a centimeter long. Pins fix the layers to each other at known points, so the only drift happens between pins, where it is small enough to be eased in. Good pinning is also where the fit is decided: a notch matched 5 mm off at the pinning stage is a sleeve that twists.

What do you need to pin fabric?

• Fine, sharp dressmaking pins, 30–35 mm (1 1/4 in) long, with glass heads. Glass heads survive the iron; plastic ones melt and smear.
• Extra-fine pins (0.5 mm) for silk, satin and lawn, where a standard pin leaves a hole.
• Ball-point pins for knits, which push between the loops instead of piercing them.
• Sewing clips for leather, oilcloth, laminated cotton, thick fleece and the bulky layers of a tote bag, which pins would mark or not go through. The pins vs clips vs pattern weights post compares them.
• A magnetic pin dish on the table next to the machine, so pulled pins land somewhere other than the floor.
• Pattern weights for cutting, when you prefer not to pin the paper at all.

Throw out any pin that is bent, blunt or rusty. A blunt pin snags fabric; a bent one holds the layers at an angle.

How do you pin a seam, step by step?

1. Lay the two pieces right sides together on a flat surface, not in your lap. Line up the raw edges along the whole seam.
2. Pin the two ends first. Push each pin in through both layers about 1 cm (3/8 in) in from the edge, at a right angle to the seam, and bring it back up so that the head sits outside the raw edge.
3. Pin every notch and dot next. The notches are where the pattern maker says the pieces must meet; match them exactly, even if the fabric between them looks uneven for now.
4. Fill in between, every 5–8 cm on a straight seam, smoothing the fabric flat with your free hand between each pin. If one layer is longer than the other between two pins, that is ease; distribute it evenly with more pins rather than letting it bunch at one end.
5. Check the underside. Turn the seam over and make sure the lower layer's edge is still level with the upper one. A pin that caught only one layer is the most common cause of an edge that slips.
6. Sew, pulling each pin out as the foot reaches it, before the needle gets there. The sew a straight seam guide shows the rhythm.

Tip: Pin on the table, then carry the seam to the machine. Pinning at the machine means pinning fabric that is hanging off the bed and stretching under its own weight.

Should pins go across the seam or along it?

Across (perpendicular) for sewing. Each pin then holds a short stretch of the seam exactly, it is easy to pull out with one hand while the other guides the fabric, and the head sticks out past the edge where you can reach it. Pins placed along the seam line hold a longer stretch, but they are hard to remove under the foot and tempting to sew over.

Along the seam has two uses: holding a hem or a bias binding while you press it before sewing, and holding pieces while you check a fit, where the pin acts like a line of stitching.

Head toward the edge, point toward the body of the garment, so the heads are always on the side you pull from.

How far apart should pins be?

More pins are not always better. Each pin holds the fabric at a point, and on a stable fabric a pin every 3 cm creates small bubbles between them. The aim is enough pins that nothing shifts, and no more.

How do you pin a pattern to fabric for cutting?

Pin the paper to the fabric inside the seam allowance, with the pins parallel to the cutting line and about 1 cm in from the edge, every 10–15 cm (4–6 in) and at every corner. Start by pinning the two ends of the grainline arrow after measuring their distance to the selvage, so the piece cannot rotate, then the corners, then the edges. Push each pin through the paper and both layers of fabric, catch no more than 1 cm of fabric on the point and bring it back up, so the layers stay flat. Pins that scoop too much fabric lift the piece and shorten it by a few millimeters, which matters on a small piece like a cuff.

On fine fabric, or when you cut with a rotary cutter, use weights instead and keep the pins for the seams. If you pin, pin within the allowance so any holes are cut away or sewn into the seam.

How do you pin curves, ease and slippery fabrics?

On a curved seam such as a neckline to a facing, pin with the fabric supported on the table, placing the pins so that each one is at a right angle to the curve at that point. The two edges have different lengths on a princess seam; match the notches and let the fabric curve between them, clipping the concave edge a little if it refuses to lie flat.

To pin a sleeve cap, put the sleeve inside the armhole with the sleeve on top, match the underarm seam, the shoulder notch and the front and back notches, then spread the extra length of the cap between them with pins every 1–2 cm. The set-in sleeves guide goes through the full sequence.

For a gathered edge, pull the gathering threads to the right length, pin at the ends and the quarter marks, then even out the gathers between pins.

On slippery fabric, pin more often with extra-fine pins and, if the seam still creeps, hand baste it with long stitches and remove the pins before you sew; basting takes two minutes and solves more problems than any pin. The sewing slippery fabric post has the rest.

Common mistakes when pinning

• Sewing over pins. A pin under the needle bends, breaks the needle or chips the hook. Pull each one out as it arrives.
• Pinning on your lap, with the seam stretched over your knee.
• Catching one layer only. Check the underside before sewing.
• Scooping too much fabric with each pin, so the layers bunch.
• Skipping the notches and pinning from one end, then finding 2 cm of extra fabric at the other.
• Stretching knits as you pin, so the seam ripples after sewing. Lay the knit flat and relaxed and pin what is there.
• Ironing over plastic-headed pins, which melt onto the fabric.

When should you use clips or basting instead of pins?

Use clips on anything a pin would mark or not pass through: faux leather, oilcloth, laminated cotton, heavy canvas, the many layers of a bag strap, and the binding on a quilt. Use hand basting when accuracy matters more than speed: inserting a zip, matching a plaid, easing a sleeve cap on a fabric that shows every pucker, or sewing silk. Use weights instead of pins for cutting fine or slippery fabric. For an ordinary seam on an ordinary woven or knit, pins remain the fastest and most accurate tool there is, as long as they go in across the seam and come out before the needle.