How wide should seam allowances for boning channels be?

How wide should seam allowances for boning channels be? How do you even know where to start?

Since I’ve covered adding seam allowances for 3 key parts of the corset in the tutorial “How wide should corset seam allowances be?” , you know that seam allowance width greatly depends on the width of the boning used in the corset. There is the answer! You start with the boning!

This tutorial focused on calculating the seam allowance width specifically for welt seam as boning channels methods of corset construction. Check out the “Welt Seam Method Strength Layer with Floating Lining” tutorial, to find out more on this boning channel option.

When you know how the finished boning channel should look like, what parts it will have, how it will be made and what boning will you use, this becomes only a mater of adding up all of the values.

Step by step, you will learn and understand how to make corset. Enjoy the ride!

Happy sewing!

Free corset patterns

Aside from the instructional tutorial being available online, it can also be DOWNLOADED as a PDF file for offline viewing.

Tutorial on how wide should seam allowances for boning channels be

Before you can start making a corset, you need make a plan. This plan includes adding seam allowances and we can’t do that all willy-nelly.

In this tutorial, not only will I give you the formula for calculating the seam allowance width for boning channels. I will explain it all so you can understands the reasons why.

Intro in to the importance of choosing the right seam allowance width

When making corsets, seam allowances can be used for so much more than making it possible to stitch the pieces of fabric together.

We can use them to create boning channels!

Seam allowance width directly depends on the boning width, thickness and corset construction method.

This tutorial covers the basic corset construction of using welt seams for creating boning channels.

Instructions on how to measure boning width and thickness

Start by choosing your boning and measuring its width (and thickness if it is thicker than 1mm or 3/64”).

When measuring spiral steel boning, measure the widest points on both sides.

You don’t need a caliper to measure the thickness. It’s not necessary to be that precise.

This is your starting point because the seam  allowance needs to at least cover the bone.

Defining different parts of the welt seam boning channels

This is the anatomy of the finished welt seam boning channel.

Distance between seam line and first line of top stitching

Distance between the Connecting Seam and Topstitch 1 should be between 1 & 2 mm or 3/65” & 5/64”.

The purpose of adding this topstitch line is to lift some of the stress from the Connecting Seam.

Instructions on calculating the boning channel width

Distance between Topstitch 1 to Topstitch 2 is the width of the boning channel.

Channel width is equal to:

Bone Width
Bone Thickness
1 to 2mm
3/64” to 5/64”

Distance between the second top stitch to fabric raw edge

Last but not least, distance between the Topstitch 2 and the Raw Fabric Edge.

It is very important because we don’t want our efforts to literally fall apart.

This width should be 3 to 6mm or 1/8” to 1/4”, not more.

Formula for calculating the seam allowance width for boning channels

With all said and done, seam allowance width consists of:

1 to 2mm                              /                               3/64” to 5/64”
+                                                                                 +
Bone Width                         /                                 Bone Width
+                                                                                 +
Bone Thickness                  /                              Bone Thickness
+                                                                                 +
1 to 2mm                             /                               3/64” to 5/64”
+                                                                                 +
3 to 6mm                            /                                   1/8” to 1/4”

End of the tutorial on how wide should seam allowances for boning channels be

Add everything up and test what ever you end up with by making samples using the same materials your corset will be made with.

Make sure you make sample for both straight and curved seams.

It is completely fine to clip in your seam allowances over curves to allow the fabric to ease over the curves.

Happy sewing!!!