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By The Numbers Fabric Air Permeability and MVTR are Closely Related, Just Not How You Might Expect

This work explores the relationship between air permeability and MVTR in fabrics that do not include a waterproof membrane.

By The Numbers- How Much Wind Penetrates Your Air Permeable Outer Layer at Hiking and Running Speeds (Updated)

Stephen Seeber helps us answer the question, "do air-permeable garments allow a noticeable amount of ventilation while hiking or running?"

By the Numbers: The Myth of Air Permeability in Windshirts

If one of your objectives in selecting a windshirt is eliminating moisture vapor, your selection should rely more heavily on Moisture Vapor Transmission Rate (MVTR) than Air Permeability Measurements (APM / CFM).

By The Numbers: What’s the Best Base Layer Fabric? Wool vs. Alpaca vs. Polyester

In this paper, I subject base layers in various weights made from merino, merino blends, and alpaca to the suite of tests I have developed to evaluate base layer performance. I then compare the performance of these base layers with those of the polyester base layers I have recently reviewed. We also see if my preconceived notions about merino hold water. Finally, we will see how to choose the fiber for our base layers.

By The Numbers: Patagonia Capilene Thermal Weight vs. Patagonia Capilene Midweight Performance Comparison

How does Patagonia Thermal Weight Capilene stack up against Midweight Capilene?

By The Numbers: Testing the Performance of Mountain Hardwear AirMesh Garments

Is Mountain Hardwear AirMesh a breakthrough product or a prisoner of wicking base-layer physics?

Why is my base layer soaked?

Sometimes a wet base layer just can't be avoided. Soaked-based layers happen. Here is why it will happen to you.

By the Numbers: Compression Resistance of PrimaLoft Gold vs. Climashield Apex (Part 4)

PrimaLoft Gold outperforms Climashield Apex as the more resilient (durable) insulation, capable of retaining more of its original warmth and loft in response to repeated compression.

Do moisture-wicking fabrics work?

Moisture-wicking fabrics (base layers and underwear) are designed to move sweat away from the skin. In this study, we test if Polartec and other base layer fabrics meet manufacturer claims.

Synthetic Insulation Degradation Part 2: Thermal Performance vs. Compression

How bad does high-loft synthetic insulation (Climashield Apex and Primaloft Gold) degrade when subjected to repeated compression cycles? What's the impact on backpacking gear and apparel?

By the Numbers: the Search for a High-MVTR Waterproof Breathable Shell Jacket

A high MVTR waterproof-breathable shell jacket may be the holy grail that can replace both a wind shirt and a rain jacket. Do they exist, and where do we find them?

By the Numbers: Crushing It – How Bad is Thermal Degradation in Synthetic Insulation?

In part two of this investigation, we see what happens when you crush insulation beneath a stack of concrete pavers - again and again.

The Search for a Fleece Replacement – A Close Look at Active Insulation and the role of MVTR

What is MVTR's role in active insulation garments?

Air permeability vs. moisture vapor transmission rate (MVTR): which one impacts moisture transport more in wind and rain jackets?

This study compares the performance of four jackets made with fabrics that span a wide range of air permeability rates and moisture vapor transmission rates (MVTR). The study shows that significantly greater moisture removal can be achieved as a function of jacket MVTR than jacket air permeability.

By The Numbers: How Bad is Thermal Degradation in Synthetic Insulation?

The latest findings on thermal degradation in synthetic insulation from Stephen Seeber may surprise you in this By The Numbers column.

By the Numbers: Is Synthetic Insulation Warm When Wet?

We throw some quantitative testing at an oft-repeated synthetic insulation claim to measure the thermal performance of wet insulation.

By the Numbers: Rethinking Fleece

Stephen Seeber subjects ten fleece samples to rigorous thermal testing.

By the Numbers: Thermal Performance Measurements of Synthetic Insulations

Stephen Seeber presents measurements of several market-leading insulations along with four performance metrics to help judge their performance.

By the Numbers: If You Carry a Space Blanket, Buyer Beware

Stephen Seeber tests the infrared reflective properties of space blankets.

By the Numbers: Patagonia Worn Wear Micro Puff vs. New Micro Puff

In his new column for Backpacking Light, Stephen Seeber runs thermal testing on used and new Patagonia Micro Puff jackets.

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