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SealSkinz ChillBlocker and Over The Calf Socks SPOTLITE REVIEW

Durable and reliably waterproof socks, but have a couple of distinct drawbacks.

Overall Rating: Average

We found the SealSkinz socks to be waterproof and somewhat breathable. They fit well and are quite durable. However, the outside fabric absorbs and holds a lot of water, making them very difficult to dry out when winter camping. Also, we found the ChillBlocker socks' fleece lining had a tendency to de-laminate.

About This Rating


by Will Rietveld and Janet Reichl |


SealSkinz socks have been around for quite a few years, and are well-known for being waterproof and tough. In our Lightweight Footwear Systems for Snow Travel project (to be published soon), we evaluated the SealSkinz ChillBlocker and Over The Calf socks inside non-waterproof trail running shoes for their ability to keep feet warm and dry. How well did they do?

SealSkinz ChillBlocker and Over The Calf Socks SPOTLITE REVIEW - 1
The SealSkinz Over The Calf Sock (left) is 15 inches high and has a Coolmax fabric lining. The ChillBlocker Sock (right) is 11 inches high and fleece lined. In each photo the left sock is turned inside out to show the lining.

SealSkinz ChillBlocker and Over The Calf Socks SPOTLITE REVIEW - 2
Close-up view of the sock linings; Over The Calf Sock (left) and ChillBlocker Sock (right).

The SealSkinz socks are a bit weighty. Both models weigh 5.4 ounces/pair in size Large. Each is a three-layer construction, with a stretchy nylon/Lycra spandex fabric on the outside covering a MVT (Moisture Vapor Transpiration) membrane. The ChillBlocker Sock has an expedition-weight Polartec Power Stretch fleece bonded to the inside, and the Over The Calf Sock has a Coolmax wicking fabric on the inside.

The Lycra spandex in the outer layer gives the socks a good bit of stretch as well as a good fit. Since these socks are designed to be worn in a non-waterproof shoe or boot, any additional socks needed for wicking or insulation should be worn inside them, and the SealSkinz have ample room to accommodate additional socks.

SealSkinz ChillBlocker and Over The Calf Socks SPOTLITE REVIEW - 3
We wore a liner sock and wool sock for warmth inside the SealSkinz socks on numerous snow hikes and snowshoeing trips and on one March 9-day canoe trip, and found the combination to be quite warm, especially when we were actively moving.

The MVT membrane is claimed to be waterproof/breathable, specifically it “lets perspiration out while preventing water from coming in”. We did some informal tests to check those claims. Our “balloon test” (blow up the sock by mouth, pinch off the top, and squeeze the sock to deflate it) indicated that the socks are somewhat breathable. They deflated with only moderate pressure. Our “immersion test” for waterproofness (stuff the sock with a white T-shirt, submerge the lower sock in a pan of water for one hour, inspect the T-shirt for wetness) indicated that both sock models are indeed waterproof (no leakage).

Our field testing confirmed that the socks are waterproof, but we found their breathability to be low at best. We weighed the socks after each snow hike or snowshoeing trip, and repeatedly measured about 0.5 to 1.0 ounce of moisture (from sweat) in a pair of insulating socks worn inside the SealSkinz. That sounds like a small amount of moisture, but it is enough to make the socks feel damp while hiking and chilly when we stopped.

We also found that the socks’ nylon/Lycra outer fabric absorbs a good bit of water. On a typical trip the socks gained 1.5 to 2.0 ounces of water per pair, mostly in the foot area in the outer face fabric. The persistent exterior wetness of the socks had a cooling effect which chilled our feet when we were less active. For example, on the canoe trip we wore the Over the Calf Socks in water shoes to keep our feet dry while wading at landings, but the wet socks kept our feet chilly as they gradually dried out. On a snow camping trip the socks were very difficult to dry out overnight.

SealSkinz ChillBlocker and Over The Calf Socks SPOTLITE REVIEW - 4
We noted some de-lamination of the fleece lining in the ChillBlocker Socks in the heel area on one sock (left) and at a seam on another sock (right). It had no effect on the socks’ waterproofness.

Overall, we found the SealSkinz socks to be reliably waterproof, but minimally breathable. We feel they are most suitable for day hiking or snowshoeing in non-waterproof shoes/boots in snowy or wet conditions.

Features and Specifications

  • Manufacturer: Danalco (
  • Sizes: S,M,L,XL (men’s 5-13, women’s 6-11)
  • Fabric: Outside layer is of nylon/Lycra spandex, lining is expedition-weight double velour Polartec Power Stretch fleece (7.3 oz/yd2).
  • Features: Fitted, durable stretchy outer fabric, moisture wicking lining
  • Weight: ChillBlocker Sock size Large is 5.4 oz/pair (153 g); manufacturer specification n/a; Over The Calf Sock size L is 5.4 oz/pair (153 g); manufacturer specification n/a
  • MSRP: ChillBlocker Sock $49.95 US, Over The Calf Sock $38.95 US


"SealSkinz ChillBlocker and Over The Calf Socks SPOTLITE REVIEW," by Will Rietveld and Janet Reichl. (ISSN 1537-0364)., 2007-02-25 03:00:00-07.