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Boning for Bustier (Bra Cup). Rigilene vs Porcelynne underwire

Hello everyone!

Now I will show two ways to sew the underbust round bone in corsets with a one-piece cup. Despite the fact that in my tutorials you mostly see the option with a curved Rigilene bone, you might replace it with a metal bone and a tunnel tape. You can see how to do it in the following video.

So, there are two ways how to make a convex, voluminous and stitched cup in the corsets with a one-piece cup: using 8 mm wide Rigilene bones or a metal underbust bone, which we use to make cut-off cups or bras.


I show very often the technique to make convex cups using Rigilene bones in my courses. We used this technique for many years in a row as it was very convenient, and we always found Rigilene bones, which were easy to give the round shape we needed. As a rule, these bones bent softly and it was possible to move a shell along strings without any problems and bend the bone to the desired diameter. I will show you how to do it a little later.

However, over the years the production of Rigilene bones began to change and they became hard in most cases and it is impossible to shape them up. No matter how much you try to pull the shell towards you, it doesn’t gather. It is impossible to work with such bones as they are not suitable for creating semicircular cup bases.

Therefore, I will show you an alternative way to make cups with metal bones. After that I will remind you the old traditional method that I used very often and showed in my tutorials. I will do it, so that you understand that you can easily replace bendable Rigilene bones with a round metal bone when you see the technique of a stitched cup in my courses.

The work on a stitched cup always starts with the marking bone positions, regardless whether we use a Rigilene bone or a round bone - the beginning is the same: mark the position of the bones as I show in my tutorials. The bone positions can vary depending on style, size and various other factors, which I certainly explain in detail in my tutorials. The only difference is that the position of the round bone is marked immediately when we use the Rigilene bone. The round metal bone is marked on the dress-form when the front pieces are sewn along the curves.

After completing all the traditional steps: stitching along the curves, pressing seams and cutting allowances off at the level of the cup, we put the corset on the dress-form and precisely align its center with the dress-form center. Next, we take the round bone that fits this garment. Please note, this bone can be of any shape - there are dozens of its varieties now. This bone can be of the usual classic shape or shortened to make a V-shaped cut, or it can be expanded for specially shaped cups. Your task is simply to choose the bone that best suits the style of your garment and fits exactly the size.

Apply the bone to its place. It is very important to correctly position the bone: its bottom should be located exactly on the underbust line. Don't forget that the bone has a front end and an end that goes into an armpit. Position the bone correctly, press it firmly with your hands, carefully trace it along the inner contour and mark the beginning and end of the bone. Repeat the same steps on the other side of the corset. Then the corset can be removed from the dress-form.

It is necessary to sew the tunnel tape on to secure the metal bone under the bust.

I take the tunnel tape and attach it along the outer side first, guided by the bone marking. I will start and finish stitching outside the seam allowance mark, i.e. from the edge of the piece, so that I don’t finish the ends of the tape.

When I reach the bust line, I begin to do a very small fullness under the tape: while stitching along the rounding, I make a small wave under the tape, i.e. I push the fabric away from me, and pull the tape.

I finish fullness when I complete the rounded area.

I move in a circle. It is sometimes necessary to do some fullness under the tape on the second rounding in some styles and it is not necessary for the others. Now I will not discuss this question, because it is completely impossible to cover all the factors in a short tutorial. There is all the information about it in the courses.

I finish the stitch and cut the excess tape.

Now, as always, all Rigilene bones are stitched along the marked lines and their ends are hidden, under the stitched round contour of the tunnel tape.

We make a running stitch on the top of the corset and it is also possible to stitch the tunnel tape instead of the curved Rigilene bone. I will not do this now.

The last operation, after stitching all the Rigilene bones along the marked lines or leaving the cup soft, is to fix the round bone or the tunnel tape in our case along the inner contour.

The final stage is to insert the metal bone.

Now we have a convex cup that will support the bust like a bra.

We just need to limit the metal bone. In order to do it we make a small (1 mm) stitch several times back and forth across the tape at the level of the bone ends.

Well, now let's remember what a curved round bone Rigilene is. Let’s stitch this bone on the other half of our mock-up and compare the results.

How to bend the Rigilene bone? Those who do not know yet - look carefully, and those who are already familiar with this technique - repeat.

Move the shell and free the string. I repeat once again: the bone should be of such quality that the shell can be easily gathered. If not, round metal bones should be used instead.

After sliding the shell, pull one extreme string and watch the Rigilene bone bend immediately. This is where the term “a curved round bone” came from. We pull the strings and the bone bends more and more, and becomes of a semicircular shape. The excess strings should be cut off.

We take the prepared bone, wrap its tip with masking tape and begin to sew along the marked line. Sew the bone along its outer side, so that you can place the ends of the bones, which form an interlacing inside the cup, under it.


When we reach the most rounded area, we begin to do fullness under the bone.

We finish fullness when we move to the straight area.

As I said, at the level of the second rounding, we do fullness under certain circumstances. You can finish sewing the bone on the bust line or before the seam allowance mark. I will end on the edge of the piece, because this is just a demo sample.

As usual, finish by stitching along the inner side of the round bone when all the bones inside the cup are stitched and their ends are hidden under the round bone.

So, two one-piece cups were made and two bust supports were sewn on the cups and this was done using two equivalent techniques.

Now you are familiar with two equivalent ways to sew a round bone in corsets with a one-piece cup. Choose the method you like best.

All the best!

Tatiana Kozorovitsky

Corset Academy


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