July 5, 2022

How to sew a bra muslin

Making a muslin or test version of your bra is a crucial step in create a well-fitting bra. Today, we’re showing you how to make a bra muslin.

Jump to another post in this series:

  1. Bra fitting guide overview
  2. How to choose your bra size
  3. How to make a test bra
  4. How to adjust the back band
  5. How to adjust the gore/bridge
  6. How to adjust the cups
  7. How to adjust the side seam angle
  8. How to adjust the straps
  9. How to adjust the underwires
  10. How to make an asymmetrical bra
  11. Additional bra making resources

The Cashmerette Willowdale Bra is a full frame underwire bra sewing pattern for large busts in sizes 28C-54J with a 4-piece cup design for vital support and lift in a beautifully rounded shape—the perfect bra if you have big boobs.

Start your bra fitting journey with the Cashmerette Bra Fitting Guide

To help you sew and fit your dream Willowdale, we’ve put together the Cashmerette Bra Fitting Guide! This post is one of the many tutorials you’ll find there, and if you haven’t yet checked out the main guide page, we recommend starting there. So much of bra fitting is interconnected, and the guide provides a checklist and order to work through the adjustments.

In this post, we’re covering how to make a muslin. Let’s get started!

What is a bra muslin?

A muslin, also known as a toile, is a test version of the garment you’re making. It’s important to make a muslin for every new pattern you try, but this is even more true when it comes to bras.

Our bodies (and boobs!) come in all shapes and sizes, and we rely on our bras to fit well and provide the support we need without hurting in the process. It can take a few tries before you perfect your bra fit and you don’t want to cut into your precious final fabric until you know you have a version of the pattern that will fit you beautifully.

What fabric should I use for a bra muslin?

You might think that you should use muslin fabric to make your bra muslin—nope!

Bra fabric comes in all weights and stretch percentages, and both of these factors can impact how the bra fits you. So the best way to determine how your final bra will fit is to simulate it with fabric that is as close as possible to your final fabric. If possible, buy extra fabric and make your muslin with the exact same fabric!

The Willowdale Bra is designed for low stretch fabrics of up to 20% stretch. It relies on this stretch to accommodate differences in bra shapes and to get a good fit. You can make it with nonstretch fabric or fabric with a greater stretch percentage, but you may need to spend more time working on the fit if you do.

As for the rest of the bits and bobs—the stretch lace for the upper cup, the power mesh for the back, and the band, underarm, and strap elastics—you should use ones that are  as close as possible to your final materials as well.

How do I make a bra muslin?

You may not want to hear it, but here’s the hard truth: when making your bra muslin, you’ll need to sew up the entire bra. Bras are designed with tension that goes in all different directions, and it’s nearly impossible to determine how a bra will fit without all of the tensions coming into play.

Some bra makers recommend making a single cup to check the cup volume, but it’s difficult to use this technique to get a true sense of the cup fit and it won’t tell you much about how the rest of the bra will fit. At the end of the day, the best approach is to sew up the entire bra.

But that said, you can take some shortcuts to save on time and materials:

  • You can make View A which has a solid body and stretch lace only on the upper cup
  • You can baste all your seams and underwire channeling
  • You can baste your elastic (using a longer zigzag or stretch stitch) and hardware to make them easier to remove and reuse
  • You can skip adding the lingerie bow
  • Do not sew any of the bar tacks that hold the underwires in place
  • You can use mismatching elastic, notions, and thread to use up leftovers from other projects (assuming they’re all similar to your final materials), or harvest materials from old bras

Ultimately, bra fitting is not a quick endeavor, and making a muslin is just part of the process. But you’ll be happy that you took the time to do it right, and you’ll end up with a much better result! Plus you’ll have gotten to practice the techniques and construction along the way which is never a waste of time.

How to make a bra fitting sample

If you’ve made one or more bras before and feel comfortable with the bra-making process, here is a more advanced way to make a bra muslin. This method, shown below by Jennifer of Porcelynne using the Willowdale Bra, allows you to construct the different sections of the bra separately and puts them all together at the very end, which means you can swap them out and make adjustments without having to sew up a whole new bra muslin.

Keep in mind that this construction method is not the same as the construction used in the pattern’s instructions.

This technique is not recommended if it’s your first time sewing a bra.

I’ve made my muslin. Now what?

Congratulations! This is an important first step in the bra fitting process. The next step is to evaluate the fit and make plans to refine it. Head to our Bra Fitting Guide to learn more!

We hope this tutorial was helpful! Drop any questions you have in the comments below.

One thought on “How to sew a bra muslin

  1. That is the most clear description of how to make a fit sample and what to do with the center gore spacing that I’ve ever seen. Very helpful.

Let me know what you think!