When you’re designing clothes made from stretchy fabrics, like swimsuits, it’s essential to ensure that the fabric stretches evenly across the body. Stretch fabrics behave differently from non-stretch fabrics, and understanding how the fabric moves and adapts to the body is key to creating garments that fit well, feel comfortable, and stay in place.
Let’s break down the main concepts to help you master designing with stretch fabrics.
Why Even Stretching Matters
Imagine a swimsuit as a tube of fabric wrapping around your body. If the fabric doesn’t stretch evenly, several things can go wrong. It might wrinkle in some areas, creating unsightly folds or excess material. Or worse, the garment might shift during movement, causing it to ride up or slip down. Both of these issues compromise comfort and the overall look of the garment.
To avoid this, you need to carefully plan how the fabric stretches. There are two main directions in which the fabric needs to stretch:
- Length (from shoulders to hips, or in the case of a swimsuit, from the crotch up to the neckline).
- Width (around the bust, waist, hips, or thighs).
These directions are referred to as vertical ease (for length) and horizontal ease (for width). Understanding these terms is crucial when designing with stretch fabrics.
Negative Ease: What It Is and Why It’s Important
In stretch fabrics, we use something called negative ease to create a snug fit. Negative ease means that the garment is actually smaller than the body it’s meant to fit. When the person puts on the garment, the fabric stretches to match their body size, creating a tight, body-hugging fit.
This is very different from working with non-stretch fabrics, where we typically add ease (positive ease) to allow for movement and comfort. With stretchy fabrics, negative ease ensures the fabric stays close to the body and doesn’t sag or shift during movement.
Negative ease is most commonly applied to the horizontal ease—around the bust, waist, and hips—because these are the areas that need to stretch to create a form-fitting garment. Vertical ease, on the other hand, is often left unchanged or reduced only slightly. This is because, while the body changes width during movement (as muscles contract and expand), its length changes much less. If the vertical stretch is too tight, it can cause the fabric to shift instead of staying securely in place.
Finding the Right Balance Between Horizontal and Vertical Ease
Designing for stretch fabrics means finding the right balance between horizontal and vertical ease. Let’s look at what happens when you adjust these two types of ease:
-
Horizontal ease: This refers to how much the fabric stretches around the body, typically across the bust, waist, hips, and thighs. If you reduce the horizontal ease too much (making the garment very tight), you risk limiting the number of people who can comfortably fit into the garment. However, for swimwear and other form-fitting clothing, a moderate reduction in horizontal ease creates a sleek, body-conforming fit.
- Example: For swimwear, you might use 8-12% negative ease horizontally, meaning the fabric pattern is 8-12% smaller than the wearer’s actual body measurements.
-
Vertical ease: This refers to how the fabric stretches lengthwise, from shoulder to crotch in a swimsuit. In most cases, vertical ease is kept close to the actual body length, or reduced slightly, because the body doesn’t expand as much in this direction. If the vertical stretch is too tight, the garment won’t move properly with the body and may pull or shift during movement.
- Example: In fashion swimwear, vertical ease is often reduced by 0-2%, but in more flexible garments like dancewear, it can be adjusted by up to 5-6%.
Why Horizontal Ease Is More Flexible
When designing for mass production, it’s important to remember that not all bodies are the same. Even within a single size (for example, a size 10), there can be variations in body measurements. This is why it’s helpful to leave a little flexibility in the horizontal ease—this allows the garment to fit a range of body shapes and sizes.
For instance, a size 10 swimsuit might be designed to fit bust measurements from 82 cm to 86 cm, even though we call it a single size. Stretch fabrics can accommodate this small range of sizes because of their elasticity. But if you reduce the horizontal ease too much (for example, making the garment fit only an 82 cm bust), fewer people will be able to wear that size comfortably.
Tighter-fitting garments (like fashion swimsuits or dancewear) are often designed with less flexibility in the horizontal ease, which results in a sleeker, more fitted look. However, this also means that these garments will fit fewer people as they are designed to conform closely to specific body measurements.
Looser garments (like surf-style swimwear or athletic wear), on the other hand, may have more horizontal ease, allowing them to fit a broader range of body types while sacrificing some of the sleekness.
The Stretch Factor: How Fabric Reacts to Stretch
When designing with stretch fabrics, it’s important to understand how the fabric behaves when stretched. Some fabrics, especially those with a high elastane content (like spandex), stretch evenly in all directions, while others may stretch more in one direction than the other.
When you stretch fabric horizontally, it might also stretch slightly vertically, and vice versa. This is known as multidirectional stretch. You need to account for this when designing your pattern. The direction in which the fabric stretches the most (known as the grainline) should go around the body. This helps ensure that the garment fits well around the bust, waist, and hips without becoming too tight or constricted during movement.
It’s always a good idea to test how your fabric stretches before you start designing. Fabrics stretch and recover differently based on their composition, so make sure you understand the fabric’s properties before finalizing your design.
Understanding Negative Ease for Different Garments
Here’s an example of how much negative ease you might apply for different types of garments:
- Dancewear: 5% horizontal ease, 6% vertical ease. Dancewear needs to be highly flexible, so the negative ease is reduced to allow for freedom of movement in both directions.
- Surfwear: 7% horizontal ease, 5% vertical ease. Surfwear requires a bit more flexibility for movement but still needs to stay secure in active conditions.
- Fashion Swimwear: 12% horizontal ease, 0-2% vertical ease. Fashion swimsuits prioritize a sleek, body-hugging fit, so there is more reduction in the horizontal ease, but little to no reduction in vertical ease to ensure comfort and range of motion.
The general rule is: the more you reduce horizontal ease, the less you need to reduce vertical ease to keep the garment’s tension balanced. If the horizontal ease is significantly reduced but the vertical ease isn’t adjusted correctly, the garment may wrinkle or shift as the fabric tries to compensate for uneven tension.
How to Determine Negative Ease
In the past, designers would test fabric by wrapping it around a body part to get a feel for how much negative ease to apply. Today, most fabric manufacturers provide detailed information about the stretch percentage and recovery of the fabric, making it much easier to calculate negative ease.
A good starting point for beginners is to use about 8-12% negative ease horizontally and no reduction in vertical ease for most stretchy fabrics like spandex. You can adjust this based on the specific fabric you’re using and the fit you want to achieve. For those just getting started, a more relaxed fit can be created by reducing horizontal ease to around 8-9% and vertical ease by around 3%, but you’ll develop your own method as you gain experience.
The Importance of Fabric Testing
Finally, remember that every fabric behaves differently. Switching to a new fabric often means you’ll need to tweak your pattern to achieve the same fit. Testing the fabric is crucial before finalizing your design. It’s helpful to have a few pattern blocks with varying levels of negative ease on hand so you can quickly adapt to different fabrics.
Conclusion: Designing Clothes that Move with the Body
By understanding how stretch fabrics behave and how negative ease works, you can design garments that fit snugly, stay in place, and move comfortably with the body. The key is balancing horizontal and vertical ease based on the fabric’s properties and the desired fit. As you gain experience, you’ll become more skilled at adjusting patterns and ease levels to create beautiful, functional garments for a wide range of body types.