Why The Mid Layer Matters During Season Changes

Layering is often a misunderstood concept in high‑visibility workwear. It is not simply about adding warmth.

Layering is about managing heat, moisture and protection as a complete system, while always maintaining conformance to ISO 20471, the standard for high‑visibility clothing. In safety‑critical environments, achieving that balance is essential.

Why the Mid Layer Matters

The mid layer is the engine room of the system.

Its primary function is insulation, trapping air to retain body heat. Air is a natural insulator, and the more effectively a garment traps it without adding excessive bulk, the better its warmth‑to‑weight ratio.

Insulation alone, however, is not enough. Mid layers must also allow moisture to escape. If perspiration becomes trapped, wearers experience the cold, clammy feeling that quickly reduces comfort and concentration.

The goal of a mid layer is controlled thermal regulation:

• Retain warmth when static
• Release excess heat during exertion
• Maintain comfort across changing conditions

The Three‑Layer System

A high‑performing layering system consists of three distinct components:

• • Base layer – sits against the skin and helps transfer moisture away from the body

• • Mid layer – traps warm air and regulates body temperature

• • Outer layer – protects against wind and rain

Each layer plays a technical role in controlling heat and water vapour transfer. Get it right and the wearer remains warm, dry and visible. Get it wrong and the result can be discomfort, distraction and reduced protection.

Different Leo Workwear Mid Layers, Different Performance Benefits

Sweatshirts
High‑visibility sweatshirts remain a staple garment for many wearers. Leo sweatshirts combine recycled polyester for durability, colour fastness and structural stability, while cotton content enhances comfort against the skin. The result is a compliant, robust and practical garment that balances durability with day‑to‑day wearability.

Softshell Jackets
Leo softshell mid layers add technical performance. Windproof membranes help reduce heat loss, while breathable construction allows moisture vapour to escape. Stretch fabrics provide flexibility, which is essential in physically demanding roles where unrestricted movement supports both safety and productivity.

Fleece Jackets
Fleece is highly effective at trapping heat thanks to its brushed structure. Lightweight yet insulating, Leo fleeces deliver an excellent warmth‑to‑weight ratio, making them ideal for layering beneath waterproof outer shells.

Bodywarmers
Leo bodywarmers provide core insulation while preserving freedom of movement. Water‑repellent outer fabrics offer light weather resistance, and insulated linings retain warmth without unnecessary bulk.

The Halsinger Men’s Performance+ Bodywarmer (BW02) demonstrates how far mid layers have evolved. Featuring Sorona® Aura insulation, it delivers high levels of warmth while remaining ultra‑lightweight. Made using plant‑based polymers, it supports thermal comfort without compromising mobility.

Conformance at Every Stage

Compliance is one of the most important, and often overlooked, considerations.

If a waterproof outer shell is removed due to increased activity or changing weather conditions, the garment worn underneath must still maintain the required high‑visibility classification. This means sufficient fluorescent background material and correctly positioned reflective tape, in line with ISO 20471.

In environments where high‑visibility clothing is mandatory, every visible layer must stand independently compliant. This is easily achieved when using Leo garments throughout the layering system.

Designed as a System

Modern high‑visibility mid layers are not isolated garments. They are engineered to integrate seamlessly with outer shells, often via zip‑in compatibility. This allows wearers to layer up or down without sacrificing breathability, waterproof performance or certification.

Sustainability also plays a growing role. Leo EcoViz® recycled polyester fabrics and responsible insulation technologies from Sorona® mean high‑visibility warmth no longer needs to come at an environmental cost.

Designed for the Way People Work

Workers are more productive when they have the flexibility to dress for the conditions they are working in. Physical output varies throughout the day, from high‑exertion tasks that generate heat to slower or static work, where body temperature can drop quickly.

A well‑designed layering system allows wearers to adapt, adding or removing garments as conditions change while still maintaining compliance. This helps prevent overheating, excessive sweating and the cold, clammy discomfort that occurs when moisture cannot escape.

By staying thermally comfortable, workers can maintain focus, reduce fatigue and sustain consistent performance throughout their shift. Providing the right layers is therefore not just about comfort, but about supporting safety, efficiency and productivity on site.

Rethinking the Mid Layer

A well‑designed layering system ensures that warmth, breathability and visibility work together rather than against each other. The mid layer plays a central role in achieving this balance, helping regulate body temperature while maintaining the high‑visibility performance required in hazardous environments.

By selecting compliant, technically designed mid layers, organisations can ensure workers remain protected even as conditions change throughout the working day. When comfort and compliance are considered together, PPE performs as it should, supporting both safety and productivity on site.

Content created in partnership with Leo Workwear.