By The Numbers: Fun Findings For Five Fuzzy Fabrics

Introduction

Once upon a time, Polartec Alpha and then Polartec Alpha Direct were the only fuzzy fabrics. I bought a Rab Alpha jacket and later a Rab Alpha Direct jacket. I’ve been singing its praises on BPL for its high warmth-to-weight ratio and excellent breathability (MVTR).

Fast forward a few years, and more contenders have emerged. Are they just pretenders to the throne, or do they improve performance for this fabric category?

In this study, I compare the performance of Polartec Alpha Direct, Primaloft Evolve, and Teijin Octa (in three different fabric designs).

Here is what we will learn: Which has the best MVTR? Which has the best warmth-to-weight performance? Which has the highest R-value? Which requires the least drying energy, and which dries fastest? Are there specific cases where a single fuzzy fabric would offer a better solution than the others?

Here is a little of what we shall see.

• These are very different fabrics. Their construction is dissimilar, and those differences in construction help explain their performance relative to each other.
• Fuzzy fabrics can take about twice as long to dry as conventional fabrics. However, they require about the same amount of energy to dry. This means that, as they dry, at a point in time, you won’t feel as cold as you might with other fabrics. However, if you are drying them with body heat, the toll on your body will come from the amount of water trapped in the fabric, and this will be similar across all fabrics that hold a comparable amount of water.
• Fuzzy fabrics tend to work differently depending on which side faces out. This will vary depending on the fabric’s construction.

What is a Fuzzy Fabric?

Fuzzy fabrics trap more air using less structural fiber, creating open, lofty grids. This structure improves insulation efficiency and breathability but can compromise durability.

Compared to conventional base and midlayers, fuzzy fabrics, in general:

• Trap more air with less fiber.
• Have lighter fabric weights
• Show higher porosity, air permeability, and MVTR
• Retain more water when saturated
• Take longer to dry but require similar drying energy
• Are more prone to snags and abrasion

What do our Fuzzy Fabrics Look Like?

Figure 2 shows “typical” fuzzy fabric: fabrics with relatively high loft and large visible voids. Alpha and Evolve are somewhat similar: they have a loosely knit grid structure through which tufts of fiber are inserted. The tufts may have minimal twist, allowing their fibers to spread after insertion. The tufts may also be brushed to maximize fiber spread. Increased fiber spread traps more air.

Teijin Octa Warm and Light will be familiar to most readers as the fabric used in Mountain Hardwear Airmesh.  It has a denser base grid structure than the other two fabrics.  The grid is brushed on one side to provide loft to the fiber grids. The fibers are eight-lobed, hollow Octa.

Figure 3 presents a different perspective on fuzzy fabrics. Octa Thermofly fabric may be familiar to readers as the diamond-patterned insulated material used in the Arc’teryx Proton FL and the Norrona Falketind Octa jacket. Here, I analyze two weights of this fabric: 67 GSM and 98 GSM. The knitting technique used is called Russell knit. The fabric has a knit base grid with pile fibers anchored to it, creating diamond-shaped ridges. In the 67 GSM version, the ridges are very short, while in the 98 GSM version, they are noticeably longer and wider. The grid dimensions for both fabrics seem similar.

Figure 4 shows the Octa 98 lining in my Noronna Faltikind Octa. The diamond-shaped ridges and the knit of the structural grid in the open area they define are easy to understand. Octa 67 is similar, but the raised diamond stitching offers almost no relief from the structural grid.

The ridge provides a spacer standoff to trap insulating air in the open area. This can provide a unique function that will be discussed later.