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Minus33 Isolation Midweight Wool Review

Minus 33 Isolation Midweight Wool 1/4 Zip
Price:   $76 List | $75.99 at Amazon
Pros:  Least expensive merino wool, 50+ UPF protection
Cons:  Not very breathable, dries slowly, poor weight to warmth ratio, average comfort
Bottom line:  This contender is moderately priced for a merino wool, but a lackluster fit and overall underwhelming design didn't perform as well as its competitors in most metrics.
Editors' Rating:   
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Material:  100% merino wool
Fabric Weight:  230 g/m 2
Weight (size M):  11 oz
Manufacturer:   Minus33

Our Verdict

A price tag of $76 is indeed expensive for a shirt, but as far as merino wool products go, that's cheap. The price is what initially drew us in to the Minus33 Isolation, with hopes of scoring the great performance commonly associated with merino wool for significantly less dinero. This thick-skinned model is beastly, weighing the most of any model, but it didn't shred through the competition. Actually, it offered just an average performance pretty straight across the board. We hate the motto "You get what you pay for," especially when it appears to be correct…

If you're looking for the best performance from a merino wool product, or any fabric for that matter, the SmartWool Merino 250 Base Layer took home the Editors' Choice for its exceptional showing in nearly every metric. It outscored the Minus33 in each category. If the cheap price is what drew you into this model, considering checking out The North Face Warm, which ran away with our Best Buy award. For a complete list of models, award winners, tests, and analyses, head over to the Men's Long Underwear Review.

RELATED REVIEW: The Best Long Underwear and Base Layer for Men

Our Analysis and Hands-on Test Results

Review by:
Ross Robinson

Last Updated:
December 19, 2016

The Isolation Midweight Wool by Minus33 was the lowest scoring merino wool product in this review. In our opinion, Minus33 chose a great fabric, but forgot a few things when it came to quality design. It was the lowest-performing merino wool we reviewed, but also came with the lowest price tag at $76 for like-fabric products.

Performance Comparison

Faced with stiff competition  the Minus33 model didn't fare well in comparison  but still offers superior performance over fabrics like cotton.
Faced with stiff competition, the Minus33 model didn't fare well in comparison, but still offers superior performance over fabrics like cotton.


Although we generally expect heavier, thicker products to provide better insulation, this contender proved that this is not the only deciding factor for warmth. Weighing eleven ounces, this base layer placed eleventh heaviest — dead last. However, it only scored in the middle of the pack in terms of warmth. This top would benefit from a tighter fit. We found it to be a shame that this cozy, warm material was somewhat wasted on a poor fit.

The zipper garage on the Minus33 model.
The zipper garage on the Minus33 model.

This model does have a zipper garage to keep the cool metal from your neck, but we found it too floppy and awkward to be very excited about it. For a warmer midweight wool product, look no further than our Editors' Choice award winner, the Smartwool Merino 250.

Tucking this base layer into your waistband will improve its warmth to some degree by keeping the fabric closer to your body.


The Isolation Midweight Wool was the least breathable of the merino wools, and one of the lowest scoring in this metric overall. Shirts tend to be much more breathable when the fit is next-to-skin, and this model is too baggy. Also, the thick fabric makes it more difficult for moisture to be transmitted into the outer environment. In our indoor workout test, it took just over eight minutes for our skin to dry under this model. The Under Armour Base 4.0 and Helly Hansen Lifa Stripe Crew models take home the tacos in this category, scoring 9 out of 10.

We should mention that the breathability score, as all scores in our reviews, are relative amongst the selected group of products. Although this product didn't score well in this metric, it is still much more breathable than most windbreakers, rain jackets, softshells, and hardshells.

Comfort and Fit

The loose fit of this top wasn't our favorite. The sleeves easily slid back on our arms when raised, allowing our wrists and forearms to catch an extra chill. However, they tended to slide back into place when our arms were lowered, and the torso was long enough to cover our stomachs with our arms overhead. We generally preferred products with a more snug fit.

We were happy to keep our stomachs warm in this model  and the sleeves slid back into position when our arms lowered.
We were happy to keep our stomachs warm in this model, and the sleeves slid back into position when our arms lowered.

The thick seams on at the hem of the sleeves felt overboard and uncomfortable, while the thick seams running under the armpits also weren't our favorite, and the fabric was a bit itchy, being wool. Lastly, if you're looking for style, look elsewhere. This was the least flattering top of them all. While it didn't have any dramatic flaws, the Minus33 just doesn't feel very nice, especially in comparison to several other more comfortable, better fitting models, such as the Smartwool Merino 250, Rab Merino+ 160, and the Arc'teryx Rho.

Drying Speed

It took the Isolation Midweight 18 hours to go from sopping wet to completely dry, which was 50% slower than the fastest model from Helly Hansen. We contribute this largely to its thick fabric. Like the other merino wools, this top required agitation before it would become fully saturated.

We recommend staying in colder  dry temps with this top  because once it becomes wet  it takes a longer time than most to dry out completely.
We recommend staying in colder, dry temps with this top, because once it becomes wet, it takes a longer time than most to dry out completely.


The thick fabric of this base layer strikes us as quite durable, despite being made of traditionally delicate merino wool. It didn't show any signs of wear after our testing period. The seams around the arms have begun to fuzz and fray, though. The locking zipper pull tab felt chintzy, but we didn't experience any problems with it. The entire zipper was actually sewn off-center, which didn't instill further confidence in the sew-manship. The Mountain Hardwear Microchill 2.0 was the highest scoring contender in this metric, while the Arc'teryx Rho and The North Face Warm offered a high score of 8 out of 10.

Layering Ability

This contender easily slides over t-shirts and other base layers without a significant effect on mobility. When worn as a first layer under a tight jacket or mid-layer, this model moved around more than we wished for and bunched up a little in the armpits. Overall, this top layers pretty well, though the Arc'teryx Rho and Smartwool Merino 250 had higher layering capabilities.

Our favorite shirt for layering under and over products was the Rho AR  seen here acting as a second layer over the Minus33 model.
Our favorite shirt for layering under and over products was the Rho AR, seen here acting as a second layer over the Minus33 model.

Best Applications

If you're spending a significant amount of time in cool to cold temperatures without moving too much or engaging in low-intensity activities, this model might be for you. The Isolation Midweight is good for waiting in a deer stand or fishing off the side of a lake, as you can easily keep it tucked in to improve its insulation while waiting for elusive big bucks and whoppers. In cold temperatures, we definitely recommend wearing at least one more layer on top of this garment. Also, more robust upper bodies will likely appreciate the loose fit of this contender.


Costing $76, this is the least expensive wool product in our review. It's tough to find 100% merino wool base layers from any manufacturer with a lower MSRP. While it didn't perform up to snuff in a few categories, it is still valuable to folks looking for a wool top that won't break the bank.

This product didn't score as highly as most other models  but also didn't cost as much as the top dogs.
This product didn't score as highly as most other models, but also didn't cost as much as the top dogs.


The thick Minus33 Isolation Midweight Wool base layer has an intriguing price tag, but its performance didn't live up to the more expensive and more efficient models. Coming in toward the bottom of our list of competitors, we think the design of this product could stand improvement.
Ross Robinson

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Most recent review: December 19, 2016
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