AlpacaTek® Jacket: How It’s Built (And Why It Feels Different)

AlpacaTek® Jacket: How It’s Built (And Why It Feels Different)

If you’ve ever tried an “alpaca insulated” jacket and thought, this feels thinner than I expected, you’re not alone. “Alpaca insulated” can mean a few different constructions, and the build matters just as much as the fiber.

Here’s exactly how the AlpacaTek® Jacket insulation is designed, why we chose this approach, and what that means for warmth, feel, and long-term performance

The big difference: knitted alpaca yarn insulation (not loose fill)

Most insulated jackets rely on loose fiber fill (think: fluffy fibers held in place by baffles or quilting). That approach can work well, but loose fiber also has a downside: it can shift over time. Depending on construction and wear, loose fibers can migrate, clump, and create inconsistent loft in certain areas.

Our AlpacaTek® Jacket uses a knitted insulation layer made from alpaca yarn instead of loose fiber fill. This creates a more stable structure, so the insulation is designed to hold its shape and distribution more consistently over time.

In simple terms:
loose fill = can move
knitted insulation = holds together

The insulation package: weights and layers (GSM)

We spec AlpacaTek® insulation using GSM (grams per square meter) because it’s the most consistent way to quantify a layered insulation package. Denier and yarn count can vary by component and don’t capture the full construction as clearly as GSM.

Current AlpacaTek® insulation build:

  • Knitted alpaca boucle yarn insulation layer: 175 GSM

  • Two polyester support layers: 75 GSM each

  • Total insulated fabric package: ~325 GSM (175 + 75 + 75)

What does ~325 GSM feel like?
GSM isn’t a direct warmth rating, but it’s a strong indicator of overall “substance.” For a familiar reference point, many midweight fleeces fall around 200–300 GSM, with heavier fleeces often 300+ GSM. At ~325 GSM, this build is designed to feel more substantial than ultra-thin, packable insulation, while still staying wearable and mobile. Real warmth will always depend on wind, humidity, fit, and layering.

Why the polyester layers?
They stabilize and protect the alpaca insulation layer, keeping the package durable and consistent over time. Most buyers report staying warm and comfortable down to 10°F to 15°F, depending on conditions and layering.

Water resistance and “down-proof” support layers

The polyester layers in the insulated package are designed to be:

  • Water-repellent

  • Down-proof (tight enough to help prevent insulation movement through the fabric)

This doesn’t mean the jacket is “waterproof” like a hard shell, but it does mean it’s built to handle real-world winter conditions and light moisture.

What makes AlpacaTek® insulation different?
Most insulated jackets use loose fiber fill. Our AlpacaTek® jackets use a knitted layer made from alpaca yarn as the insulation, which helps it hold its structure and warmth more consistently over time.
Why not use loose alpaca fiber as fill?
Loose fiber can shift and clump inside a jacket over time, sometimes forming small “balls,” which can reduce loft and thermal performance. A knitted alpaca yarn insulation layer is more stable.
How much alpaca fill is in the jacket?
The insulation is one layer of knitted alpaca boucle yarn at 175 GSM (grams per square meter).
What is the total insulation package weight?
Two polyester support layers (75 GSM each) stabilize the alpaca fill, for a total insulated fabric package of approximately 325 GSM (175 + 75 + 75).
Is the jacket water-resistant?
Yes. The polyester layers used to stabilize the alpaca fill are water-repellent and down-proof.
What is the denier of the fabric?
Denier/yarn count are not currently available from the mill. The most reliable measurement they can provide is GSM.
Will you offer a warmer or thicker version?
Yes. We’re developing a two-layer alpaca fill version that will significantly increase thermal insulation.
How warm is it in real life?
Most buyers report staying warm and comfortable down to about 10°F to 15°F, depending on wind, humidity, layering, and conditions.

 

If you tell us your typical winter temps and whether you run hot or cold, we’re happy to recommend the best layering setup for your climate. For more questions, contact info@alpacasofmontana.com