How to Sew a Smooth Princess Seam

Sewing a smooth princess seam

Sewing curved seams when the two curves are not the same is a problem quite allot of novice sewist seem to have so this will explain one way of making a smooth curved seam. 

On a princess seam one piece is more curved than the other, these seams are usually on bust curves and side back pieces. 

The straighter edge is the inside curve and the more curved edge is the outside curve. 

This mini tutorial shows a bust curve. 

Always stay stitch your curved edges on all pattern pieces.

stay stitch 2-3mm 1/16-1/8 inch less than your seam width. 

Observe that the outside curve is much more curved than the inside curve. 

This piece is a H cup so its more exaggerated than a smaller bust cup size. 

The green line along the edge of seam allowance  is longer on the inside curve (side panel) than the green line on the inside curve (center panel). 

The red lines are the same length. So you need to ease the two pieces together for a perfectly aligned seam. 

We are using the green lining fabric in this pic as it’s easier to see the cut notches /snips on plain fabric.

Snip cuts into the seam allowance up to the stay stitching every 12 to 15mm (1/2″).

Pin and sew the seam, with the outside curve on the bottom, easing the inside curve center panel around the curve.  Sew slowly.

As you can see in this pic, the cuts allow the outer edge to open up as you join the seam.

In a dress like this, the seam will be pressed open, but if you are using a princess seam as part of a corset the seam allowance will be folded towards the back and top stitched.

Use a sewing ham and pressing cloth to carefully press your seams.

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