Polartec FAQ: Thermal Pro, Grid Fleece, and the Questions a Fabric Sourcing Pro Actually Gets

In my role coordinating technical fabric orders for outdoor brands and military prototypes, I've handled 200+ rush orders—some with 36-hour turnarounds. This FAQ is the one I send clients when the same questions keep coming up. It covers the Polartec basics, the difference between Thermal Pro and grid fleece, and the fabric questions that sound silly but aren't (like whether fleece can stop a bullet).

1. What is Polartec, actually?

Polartec is a textile brand, not a single fabric. It started as the company that commercialized modern fleece, and today it's the name on a bunch of proprietary knits: Thermal Pro, Power Stretch, Power Dry, Alpha, Neoshell, and grid fleece, to name a few. When you see "Polartec" on a garment, it means the fabric was made to a spec and tested by Polartec's quality program. That matters for B2B buyers because it gives you a consistent baseline for weight, stretch, and durability.

What Polartec is not: it's not "just fleece." The differences between product families are real. If you're sourcing a Polartec® Thermal Pro™ mockneck vest, you're working with a multi-denier knit that traps air differently than a basic polar fleece. That's the first thing I tell clients: don't choose the product family based on the name. Choose based on the end use.

2. What's so special about a Polartec® Thermal Pro™ mockneck vest?

Thermal Pro is one of the most versatile insulation fabrics Polartec makes. It uses variable-height knit loops to create loft—basically, pockets of still air. That's how it stays warm without being heavy. I used to think heavier fleece was automatically warmer. Then a client spec'd a Thermal Pro mockneck vest for a spring-layer system, and the total garment weight came in at nearly half of the standard fleece jacket it replaced. The warmth was comparable for active use. (Based on Polartec's published product family descriptions, accessed February 2025.)

A mockneck vest with Thermal Pro is popular for outdoor brands because it works as a midlayer or standalone. From a sourcing standpoint, the key is specifying the exact weight and face fabric. Don't just write "Thermal Pro." Write "Polartec Thermal Pro, with the exact weight and knit construction specified." Trust me: the factory needs that detail.

3. What's different about a Polartec grid fleece hoodie?

Grid fleece is the fabric on the inside of a hoodie that has a waffle-like pattern. The raised grid creates insulation while the lower areas allow moisture vapor to escape. That's why a Polartec grid fleece hoodie is a go-to for high-output activities like hiking or ski touring. It breathes better than a dense fleece and dries quickly.

A common mistake is using grid fleece for a casual hoodie where you want wind resistance. It's not a windproof fabric. It's a breathable insulated layer. If you need wind protection, pair it with a shell—or choose a different Polartec product like Power Shield. When I triage rush orders, I ask: "What is the person doing while wearing this?" That one question eliminates half the wrong fabric specs.

A couple of years ago, I weighed a "good enough" grid fleece substitute that was $1.80 per yard cheaper. The upside was saving $540 on a 300-yard order. The risk was pilling and inconsistent stretch. We passed on it. Later, a competitor who took that substitute had a whole run rejected. The $540 saving wasn't worth the brand damage.

4. Can Polartec stop a bullet? (And what does Kevlar have to do with it?)

No. I get this one more than you'd expect, normally because someone saw "technical fabric" and assumed it's all ballistic-grade.

Bulletproof Kevlar fabric is a completely different product. Kevlar is an aramid fiber used in body armor and protective gloves. Polartec is insulation. A fleece jacket won't stop a round—it might barely slow down a BB pellet. If you need ballistic protection, you need to spec bulletproof Kevlar fabric in the appropriate areal density and with the right hard armor plates. I've had one client ask me to source "Polartec body armor." There's no such thing.

To be clear, Kevlar is a DuPont trademark, and ballistic vests are tested against NIJ standards in the U.S. (Source: NIJ, nij.ojp.gov). That's outside my lane, and it's outside Polartec's.

5. Is bamboo viscose a performance fabric?

Not in the way Polartec is. Bamboo sheets viscose, or bamboo rayon, is popular for bedding because it's soft, drapes well, and the bamboo grows fast. But "viscose from bamboo" is a process, not a performance claim. It's a regenerated cellulosic fiber—basically wood pulp (or bamboo pulp) dissolved, extruded, and spun into fiber.

For outdoor apparel, bamboo viscose doesn't have the same structure, durability, or moisture-management testing as a polyester knit like Polartec. That doesn't mean it's bad. It means you're comparing a bed sheet to a climbing jacket. They don't belong in the same conversation. When a client asks me to "use sustainable fabric," I ask what the garment needs to do. Then we talk about recycled polyester, wool, or responsibly sourced down—not a material that happens to sound natural.

6. How to shrink modal (and why it doesn't apply to Polartec)

Look, if you want to know how to shrink modal: hot wash and high heat. Modal is a semi-synthetic cellulosic fiber, often from beech wood. It can shrink and lose shape under aggressive washing and drying. A 100% modal shirt might shrink 3-5% in length the first time you dry it hot. That's the answer, but be careful: it can also warp the seams and create wavy hems.

Polartec is different. Most Polartec fleece is made from polyester, which resists shrinking far better. That said, high heat can still damage the knit and face finish. I'd rather have a client ask about shrinkage before ordering 500 yards than after we've cut it. My rule: if you want to shrink a garment, test it on a sample first. And if you're shrinking modal intentionally, do it before you sew it, not after.

7. When do I need a rush order for Polartec?

This is where I live. In March 2024, a client called at 9 a.m. needing 300 yards of grid fleece for a military prototype due the next morning—normal lead time was two weeks. We found 240 yards locally, paid a $600 courier fee on top of the $8,400 fabric cost, and delivered enough to complete the fit sample. The alternative was missing the submission window.

I'm not going to tell you rush orders are always worth it. The risk is paying extra and getting the same fabric you could have had on time if the planning had been better. Here's the thing: when a rush order makes sense, the bottleneck is almost never the fabric. It's the confirmation process. I've built a 48-hour buffer into every standard order because of one $50,000 penalty clause in 2023. That lesson cost us a lot more than the buffer ever will.

There's something satisfying about hitting a 36-hour turnaround when everyone said it couldn't be done. But the real win is making sure you never need one.