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Elastic Guide: Choosing the Right Type & Width for Your Sewing Projects
Elastic might seem like a small detail — but it can completely make or break your project.
The right elastic gives your garment structure, support, and longevity. The wrong one? It can stretch out, twist, or lose shape after just a few wears.
If you’ve ever felt unsure about which elastic to use, this guide breaks it all down — simply and clearly.
The Most Common Types of Elastic
Knit Elastic
Best for: Everyday garments, waistbands, light stretch projects
Knit elastic is soft, flexible, and easy to work with — making it a popular choice for beginners. We have it in white and black.
Why you’d use it:
Doesn’t narrow as much when stretched
Comfortable against the skin
Great for waistbands in loungewear or casual garments
Keep in mind:It’s not designed for high tension or long-term exposure to water, chlorine, or sun.
Braided Elastic
Best for: Casings in underwear, swimwear, or sportswear
Braided elastic is made from tightly woven fibres in a rope-like braid. Unlike knit elastic, it narrows as you stretch it, which can cause puckering or twisting if sewn flat.
Why you’d use it:
Holds strong in lengthwise stretch
Perfect for enclosed casings where the fabric protects it
Tip: For most exposed swim edges, rubber elastic is still the preferred choice due to its superior hold, water resistance, and recovery.
Non-Roll Elastic
Best for: Structured waistbands, areas that need stability
Non-roll elastic is firmer and holds its shape really well.
Why you’d use it:
Prevents twisting inside casings
Great for thicker waistbands
Adds structure to garments
Keep in mind:It’s less flexible than knit elastic, so it’s not ideal for projects that need a lot of stretch and recovery.
Clear Elastic
Best for: Stabilizing seams, lightweight stretch fabrics
Clear elastic is thin, transparent, and often used behind the scenes.
Why you’d use it:
Stabilizes shoulder seams
Adds light support without bulk
Great for delicate or sheer fabrics
Keep in mind:It’s not strong enough to act as the main support elastic in garments like swimwear.
Rubber Elastic (Swim Elastic)
Best for: Swimwear, activewear, high-performance garments
This is the go-to elastic for anything that needs to withstand water, movement, and repeated wear.
Why rubber elastic is best for swim:
Chlorine + saltwater resistant → won’t break down like knit elastic
Superior recovery → snaps back into shape even after heavy use
Stronger hold → keeps suits secure without sagging
Durability → made to handle sun, water, and stretching
Unlike knit elastic, which can lose elasticity and become “wavy” over time in swim, rubber elastic is designed specifically for these conditions — which is why it’s essential for a long-lasting swimsuit.
Common Elastic Widths & When to Use Them
Choosing the right width is just as important as the type.
6–8mm (¼”–⅜”)
Leg openings in swimwear
Necklines and armholes
Lightweight, subtle finishes
10–12mm (⅜”–½”)
Light support areas
Bralettes or soft tops
Some swim applications
19mm (¾”)
Waistbands
Underbust bands
Areas needing more hold and structure
Common Mistakes to Avoid
Using knit elastic for swimwearIt might seem easier to sew, but it won’t hold up over time in water.
Choosing the wrong widthToo wide = bulky seamsToo narrow = not enough support
Stretching elastic too much while sewingThis can cause puckering or overly tight edges. Aim for consistent, controlled tension.
Final Thoughts
Elastic isn’t just a finishing detail — it’s a core part of how your garment fits, feels, and lasts.
Once you understand the differences, choosing the right elastic becomes second nature — and your projects instantly look and perform better.
And when it comes to swimwear? Rubber elastic is always the way to go.
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