What Is a Hong Kong Seam? (And How to Sew This Couture Finish Step-by-Step)

If you’ve ever opened a beautifully made jacket and noticed the inside looked as refined as the outside, you’ve likely seen a Hong Kong seam finish.

This couture technique wraps the raw edge of a seam allowance in bias tape, creating a clean, polished interior — especially useful for unlined or partially lined garments.

It’s practical. It prevents fraying. And once you learn it, you’ll use it constantly.

What Is a Hong Kong Seam?

A Hong Kong seam is a seam finish where the raw edge of each seam allowance is bound with bias tape.

Unlike a fully bound seam (where both allowances are enclosed together), a Hong Kong finish:

• Presses the seam open

• Binds each seam allowance separately

• Leaves a clean, lightweight finish

It’s ideal for:

• Unlined jackets

• Skirts with partial lining

• Lightweight trousers

• Medium-weight fabrics that feel too bulky for full lining

It prevents fraying while keeping the garment breathable and structured.

What You’ll Need

To practice a Hong Kong finish, gather:

• Bias tape or bias strips (1 1/4″–1 1/2″ wide is ideal for most seam allowances)

• Matching thread

• Two fabric scraps (6″ x 6″ pieces work perfectly for practice)

• Pins or clips

• Iron and ironing board

• Thread snips

• Straight ruler

• Optional but highly recommended: a tailor’s clapper

Choosing the Right Bias Tape

Bias tape quality matters more than most sewists realize.

You’ll typically encounter:

1. Lower-quality store-bought bias
   Sometimes too flimsy or translucent, which can ripple when stitched.

2. Self-made bias strips
   Cut on the 45° angle of your fabric — perfect when you need an exact color match.

3. Higher-quality store-bought bias
   Often the most reliable — stable enough to stitch cleanly while still folding smoothly.

The bias should:

• Hold its shape

• Fold easily around the seam allowance

• Not fight curves

• Not ripple under stitching

How to Sew a Hong Kong Seam (Step-by-Step)

Step 1: Sew and Press the Seam Open

Stitch your seam normally with right sides together.

Press the seam allowance open so it lies flat.
Flat pressing at this stage prevents bulk later.

Step 2: Attach the Bias to One Seam Allowance

• Align the raw edge of the bias tape with the raw edge of one seam allowance.

• Stitch approximately 1/4″ from the edge.

• Backstitch at beginning and end.

Step 3: Press and Trim (Optional)

Press the bias away from the seam allowance.

If your fabric is bulky, trim about 1/8″ from the seam allowance edge before wrapping to reduce thickness.

Step 4: Wrap the Bias

Fold the bias over the raw edge of the seam allowance to the underside, fully encasing the edge.

Press to hold the fold in place.

Step 5: Stitch in the Ditch

From the right side of the garment, stitch in the ditch — directly next to the seam where you attached the bias.

This secures the folded edge underneath.

Go slowly around curves and backstitch to secure.

Repeat for the other seam allowance.

Two Secrets to a Truly Beautiful Hong Kong Finish

1. Pressing at Every Stage

Pressing determines whether this finish looks couture or homemade.

Press:

• After sewing the seam

• After attaching the bias

• After wrapping the bias

For the flattest result, use a tailor’s clapper after steaming. Place it over the seam for 5–10 seconds while it cools. This sets the fibers and prevents ridging.

Use this especially on:

• Side seams

• Jacket seams

• Any visible interior seam

2. Match Bias Weight to Fabric

If the bias is too flimsy, it ripples.

If it’s too thick, it resists curves and adds bulk.

Choose bias that supports — not dominates — your fabric.

Where Hong Kong Seams Shine

This finish is particularly effective on:

• Unlined jackets and toppers

• Skirts with partial lining

• Lightweight trousers

• Garments where the interior may be visible

Using a contrasting bias color is a subtle designer detail that elevates the garment without adding complexity.

Practice Before You Use It in a Garment

This technique improves dramatically with repetition.

Practice on scrap fabric until your hands learn the rhythm:

Stitch → Press → Wrap → Stitch.

Once you understand the flow, it becomes second nature.

Where You’ll See It Used in Our Patterns

The Hong Kong seam appears within select construction steps inside the Design Secrets program — particularly in Module 6: Camelot — The Poised and Polished Designer.

The Camelot Skirt and Camelot Blazer incorporate this finish in areas like the side seams, where a clean, bias-bound interior enhances an unlined design.