What materials should you avoid in knitwear?

Over the years, I’ve touched thousands of knitwear pieces. Some feel amazing and last for years. Others look fine at first but stretch, pill, or make the skin itch after just a few wears. Whenever I see this, I know the problem is almost always the material.

You should avoid knitwear made with low-quality synthetic fibers (cheap acrylic, low-grade polyester), unblended 100% rayon or viscose, untreated coarse wool, and fabrics with poor dyeing or finishing. These materials tend to pill, lose shape, or feel uncomfortable on the skin.

When I guide my clients through material choices, I always tell them that bad yarn is the fastest way to ruin a good design.

Table of Contents

1. Why is cheap acrylic something to watch out for?
2. Should you avoid low-quality polyester in knitwear?
3. Why are 100% rayon or viscose knits risky?
4. Can coarse wool make knitwear uncomfortable?
5. Should you avoid heavily embellished or laminated knit fabrics?
6. Why do poor finishing and dyeing matter as much as material?
7. Best fibers to avoid in knitwear (summary)
8. Conclusion

Why is cheap acrylic something to watch out for?

Acrylic can be useful in blends, but on its own it can disappoint.

Cheap 100% acrylic knitwear pills quickly, holds static, traps heat, and can feel rough on the skin. It’s inexpensive to produce, but low-end versions age poorly.

I’ve seen sweaters that looked nice on the rack. After a few washes:

• Pilling appears all over the surface
• The shape stretches and never recovers
• It traps heat and makes you sweat indoors

Blended acrylic (for example, 70% acrylic / 30% wool) can work. But low-grade, pure acrylic is best avoided.
To understand why, refer to acrylic fiber properties explained.

Should you avoid low-quality polyester in knitwear?

Yes, if breathability and comfort matter.

Cheap polyester yarn in knitwear does not breathe well and can feel plasticky. It traps sweat and can create a sticky feeling, especially in warm weather.

I sometimes use polyester intentionally for sports knits, but I choose high-quality yarns. Cheap polyester is uncomfortable for sweaters or everyday tops.

• Good for: activewear, wrinkle-resistant blends
• Bad for: thick sweaters meant for warmth and comfort

Always check the purpose before accepting polyester content.
You can read more about polyester fabrics and breathability here.

Why are 100% rayon or viscose knits risky?

They look soft, but there’s a catch.

100% rayon or viscose knitwear tends to stretch out, sag, and lose shape after washing. Without blending, these fibers lack the structure needed for long-term wear.

I once produced 100% viscose tops for a summer order. They looked great at first but hung unevenly after the first wash. Since then, I always add nylon or polyester to stabilize viscose.

• Use viscose-nylon blends (common ratio: 80/20)
• Or viscose-polyester-spandex blends for stretch
• Avoid pure viscose for fitted garments

Blending fixes most of these issues.
Reference: Viscose fiber guide

Can coarse wool make knitwear uncomfortable?

Yes, untreated wool can be a problem.

Coarse, untreated wool can feel scratchy and cause irritation, especially on bare skin. It’s warm but not pleasant to wear directly.

I’ve worn sweaters made from rough wool. They were so itchy I had to wear a shirt underneath. For premium comfort, merino or cashmere is a better choice.

• Choose merino wool (finer fibers, softer feel)
• Or wool blends (wool mixed with nylon or acrylic)
• Wash and finish wool properly to soften it

Learn more about wool fibers from The Woolmark Company.

Should you avoid heavily embellished or laminated knit fabrics?

For comfort and longevity, yes.

Knitwear with heavy laminated coatings, glitter applications, or thick plastic prints can lose flexibility. It may crack or peel and stop the fabric from stretching naturally.

I’ve seen fashion knits where the coating stiffens after one wash. These designs look trendy but don’t wear well over time.

• Sequins, beads, and heavy plastic prints look good for short-term fashion pieces.
• For everyday wear, these embellishments reduce comfort and durability.

Why do poor finishing and dyeing matter as much as material?

Even good fibers can fail if the finishing is bad.

Poor finishing (like low-quality dyeing or no preshrinking) makes knitwear fade, shrink, or lose color quickly.

I once saw a batch of sweaters that bled dye after a single wash. The yarn was fine, but the dyeing process ruined everything.

• Ask about colorfastness testing
• Check for pre-washed or preshrunk fabric
• Smell the fabric: strong chemical smell can be a red flag

Good finishing is as important as good fibers.
Here’s a resource on fabric finishing processes you can check.

Best fibers to avoid in knitwear (summary)

From years of experience, I avoid:

• 100% low-grade acrylic
• Cheap polyester in heavy knit sweaters
• 100% rayon/viscose without blending
• Coarse untreated wool for direct skin contact
• Poorly finished or laminated fabrics

Quick reference table

Conclusion

The wrong material can ruin even the best-looking knitwear. Avoid low-grade acrylic, cheap polyester, unblended viscose, and untreated coarse wool. Always check the fabric label and test the feel before you buy.

1. Acrylic fibers explained
2. Polyester characteristics
3. What is viscose?
4. The Woolmark Company – wool properties
5. Fabric finishing processes