Why Clipping Your Seam Allowance Is Important ~ Part 3: Convex Curves.

In part 1 we looked at how close to clip your seam allowance to your stitch line as well as two ways to clip.  In part 2 we looked at why it’s important to clip your concave curves  …

To recap … a convex curve curves upwards …

Clipping-curves-conves In this picture I have clipped the paper and coloured every alternate section to highlight what is happening.  When you fold over the seam allowance, each section overlaps, the further apart your clips are from each other the more each section overlaps.


Now lets have a look at this in fabric.

Convex-curve-fabric Now lets turn this to the right side without clipping the seam allowance and see what happens.

Convex-curve-fabric- turned-no-clipping

Doesn’t look to bad in the picture, but in real life if you handle this you will feel some bumpiness along the outer edge, so lets have a look at the inside to see what is causing this.


Without clipping the seam allowance, the fabric is rippling.  If I pressed this, it could leave marks on the outside, and the edges wouldn’t be nice and smooth because of the bulky seam allowance.

So, how will this change when we clip the seam allowance?


Now the segments of the clipped seam allowance are overlapping and laying flatter.  If you are using a thick fabric like fleece or denim, cutting notches along the seam allowance would work better as it removes the bulk altogether.

Convex-curve-fabric- turned-cliped

Now my piece is laying nice and flat even though I have not pressed it.

Now lets have a look at this with an actual pattern piece.  For this I’m using the lower section of this pattern piece for the front flipper from my  seal pattern, Ciel.


And just the end section in fabric …


To see what happens when we turn this without clipping, let’s first take a peak at what’s happening to the seam allowance.


 At the very end of the flipper, those ripples are getting pretty bunched up.  So, how does that look from the right side?


Again, what’s going on here isn’t all that clear in a picture, but if you could feel it you would find a wad of fabric bunched up in the end.  For something that’s going to be stuffed, this may not be the end of the world to just leave it, but if this was for something that wasn’t going to filled  with stuffing, it would be a problem, especially in a thicker fabric.


After clipping the seam allowance, all that fabric is sitting flatter, however the very tip of the flipper is still a little crowded because of the tight convex curve.  By cutting notches, some of the bulk is removed.  To remove even more bulk, trim the seam allowance in this section to about 3 or 4 millimetres.


And finally, our convex curve, all nicely clipped and laying flat and smooth, just how we want it too 🙂

Is there a technique or tool you’re not sure about?  Leave a comment below, I love to know what your’e interested in learning.

Happy sewing … signiture




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