What Makes a Good Smock? Understanding Waterproof & Breathability Ratings

When you’re working outdoors, your clothing needs to work as hard as you do. A good smock isn’t just about keeping you dry—it’s about balancing waterproof protection with breathability, ensuring you stay comfortable in all conditions. In this post, we’ll break down waterproof ratings, breathability, and why details like YKK zips matter, so you know exactly what to look for in a high-quality smock.

How Waterproof Is Waterproof? Understanding the 10,000mm Rating

If you’ve ever shopped for outdoor clothing, you’ve probably seen waterproof ratings listed in millimetres (mm). But what does 10,000mm waterproof actually mean?

This number measures how much water a fabric can withstand before it leaks. Imagine placing a 10,000mm (10-metre) column of water on the fabric—it won’t let water through until that pressure is exceeded.

Here’s how waterproof ratings compare:

• 5,000mm – Suitable for light rain and showers.
• 10,000mm – Ideal for heavy rain and prolonged wet conditions.
• 20,000mm+ – Extreme weatherproofing, often used in mountaineering gear.

A smock with 10,000mm waterproofing (like ours) is designed for long hours in the rain, keeping you dry even in tough conditions.

Why Breathability Matters: The 5,000g/m² Rating

Waterproofing is crucial, but without breathability, you’ll end up drenched from the inside out. Breathability ratings (measured in grams per square metre per 24 hours) tell you how much sweat and moisture can escape through the fabric.

• 3,000g/m² – Low breathability, fine for occasional wear.
• 5,000g/m² – A good balance of waterproofing and breathability for active use.
• 10,000g/m²+ – Highly breathable for intense activity, such as sports or hiking.

With a 5,000g/m² breathability rating, our smock allows moisture to escape while keeping rain out, making it ideal for farmers, outdoor workers, and anyone who spends long hours in unpredictable weather.

The Importance of YKK Zips: Why We Use the Best

When you rely on a smock for work, every detail matters—including the zips. That’s why we use YKK zips, widely recognised as the gold standard in zippers.

What Makes YKK Zips the Best?

• Unmatched Durability – YKK zips are designed to last, even in tough outdoor conditions.
• Smooth, Reliable Action – No frustrating snags or breakages when you need to zip up quickly.
• Self-Lubricating Design – Over time, YKK zips actually get smoother with use, unlike cheap alternatives that stiffen or break.

A zip might seem like a small detail, but when you’re working outdoors in the rain, having a reliable, easy-to-use zip makes all the difference.

What to Look for in a Good Smock

If you’re investing in a high-quality smock, here’s what you should look for:
✔ Waterproof rating of at least 10,000mm for heavy rain protection.
✔ Breathability rating of 5,000g/m² or higher to keep sweat from building up inside.
✔ Durable, high-quality zips (like YKK) that won’t break when you need them most.
✔ A fit designed for movement—not too tight, but not baggy enough to catch in the wind.

A smock built to these standards keeps you dry, comfortable, and protected no matter the weather.

Final Thoughts: A Smock That Works as Hard as You Do

Whether you’re working on the farm, in the yard, or out in the field, your smock should keep up with your day—not hold you back. By choosing a waterproof, breathable smock with top-quality zips, you’re investing in comfort, durability, and long-lasting protection against the elements.

Looking for a smock that ticks all the boxes? Check out our [Highlander Smock], designed with everything you need to take on the outdoors.