Do I Really Need a Princess Seam?

Have you ever been unsure about which method you should use to cover your molded bra cup? Figuring out which direction to take can be an overwhelming task. But that’s why I created two princess seams patterns to help alleviate your sense of uncertainty.

But, a common question that I get is: “Do I really need a princess seam or dart on my molded bra cup?”

And the answer is: It depends. I made a quick video explaining the circumstances in which you could forgo a seam or dart, and circumstances in which seams/darts are necessary.

If you’re strapped for time (or may be unable to view the video at the moment), continue reading below.

Seamless Coverage

There are two cases in which you can seamlessly and dartlessly (not a word lol) cover your molded bra cups. 

1. You can absolutely cover your molded bra cups by simply stretching fabric over your cup if you’re using a stiff molded bra cup.
2. If you prefer to use soft molded bra cups, you can only cover your cup without seams or darts if your fabric is 195 GSM or lower and if your fabric has at least 75% stretch. 

But, why?

Fabric Forces

When you stretch a piece of fabric, its natural tendency is to want to rebound back to its original state. If your fabric requires a lot of force to stretch it, then you can expect its rebounding load to be just as great.

With that in mind, imagine anchoring your fabric to the sides of your molded bra cups using straight stitches. Now the edges of your cup will experience that rebounding load.

Stiff molded cups inherently have enough structure (a.k.a. stiffness) to withstand strong rebounding loads from your fabric. In contrast, if your fabric does not fit the criteria above for your soft molded cups, your soft molded cups will deform and invert under strong rebounding loads.

That is why it is necessary to have a lightweight and highly stretchy fabric if you opt to seamlessly cover your soft molded bra cups. 

Princess Seams

So, exactly how do princess seams or darts play a role?

A seam or a dart arrests the fabric’s rebound. Rather than fabric rebounding from one edge of the cup to the other edge, it will rebound from the edge of the cup to the seam/dart. Essentially, a seam or dart can cut the rebounding load in half and the cup won’t collapse or deform.

If you need help determining which method you should use for your molded bra cups, check out this flowchart:

Clear as mud, right?

If you have any follow up questions, please feel free to continue the discussion in the comments below! I’d love to hear from you and help you determine your best method 🙂

XO,

Monica