Does Merino Wool Shrink? (The Truth About Washing Your Gear)

The short answer

Not if it's engineered for performance. While traditional "raw" wool shrinks due to fiber interlocking (felting), Estroni Merino is Superwash-treated and blended with 5% Elastane. This combination smooths the microscopic scales on the fiber and provides structural memory, making our tanks and tees machine-washable and highly resistant to shrinking, provided you avoid high heat.

1. The Science of "Felting": Why Old Wool Shrinks

Untreated wool fibers are covered in microscopic scales (cuticles). When exposed to a combination of heat, moisture, and agitation, these scales open up and "hook" onto each other like Velcro. This is called felting, and it's what causes a garment to become dense and small. Estroni uses a specialized treatment that dulls these scales, allowing them to glide past each other even in the wash.

2. The "Heat Trap": Why the Dryer is the Enemy

It’s rarely the washing machine that ruins Merino—it’s the dryer. High heat disrupts the hydrogen bonds within the protein fibers, causing them to recoil to their natural, unstretched state. Because our Classic Tank is naturally quick-drying, we recommend air-drying flat. This preserves the Elastane's elasticity and ensures the garment maintains its original length for years.

3. Why the 5% Elastane Blend Prevents "Bagging"

A common issue with 100% Merino is that it can actually stretch out (the opposite of shrinking) during wear. By blending our 17.5-micron wool with 5% Elastane, we give the fabric "recovery." This means that after a wash, the tank snaps back to its intended tailored fit rather than becoming loose or misshapen.

External Resource: The Woolmark Guide to Laundering provides a detailed breakdown of why cold-water cycles are the gold standard for protein-fiber longevity.

4. Can You "Unshrink" Merino?

If you’ve accidentally used a warm cycle, you can often "reset" the fibers. Because wool is a protein fiber (similar to human hair), soaking it in lukewarm water with a capful of hair conditioner can relax the cuticles, allowing you to gently stretch the tank back to its original shape while damp.