Black Diamond Mercury Mitts | Tested and reviewed

Tempted to make the jump from winter gloves to winter mitts? Black Diamond is making a pitch for your business with the Mercury Mitts, but do they perform well enough to deserve the outlay? Expert gear tester James Forrest is here to find out...

American brand Black Diamond makes top quality, high-performing gloves for wintry activities, whether alpinism, skiing or hiking in snow.

The brand’s pedigree is undoubted and, indeed, the Black Diamond Glissade glove (£75/$79.95) won a previous Best in Test award from Trail magazine.

Several other pairs, including the Black Diamond Guide gloves (£160/$179.95), are also well-regarded across the industry, with various accolades to their name.

But here we’ve opted to review another award-winning pair – the Black Diamond Mercury Mitts.

Summary

These gloves tick all of the boxes, if you’re specifically looking for a pair of winter mitts and understand the benefits (excellent warmth and comfort) and drawbacks (poor dexterity) of the mitt approach.

They feature a clever design, combining a weather-resistant BD.dry waterproof insert and a shell with an Empel DWR coating alongside a removable PrimaLoft Gold Cross Core liner glove for insulation. It means the Mercurys are warm, comfortable, versatile, durable and reasonably priced.

You also get good features, top quality materials and a first-rate build quality, so there’s not much to dislike with the Black Diamond Mercury Mitts. That said, the price is north of £100, they're very heavy and finger dexterity is lacking.

Design, materials and construction

The standout feature of the Black Diamond Mercury Mitts is the use of a removable liner. This liner is a mitt-style internal glove with a thick, plush fill of PrimaLoft insulation and its own waterproof shell.

In theory you can wear the liner on its own, but it’s clearly better-designed to be used inside the main mitt shell. The liner is secured in place inside the outer shell via a loop of Velcro at the liner wrist.

The Black Diamond Mercury Mitts are made from a number of different materials. The outer waterproof shell is made from 100% recycled polyester, with a BD.dry insert (Black Diamond’s in-house waterproof membrane) and a GTT Empel DWR treatment.

Black Diamond describes the shell materials as “durable but lightweight… with four-way stretch for the freedom to move”.

The insulation is PrimaLoft Gold, a 100% recycled polyester, combined with a soft, recycled fleece lining, while a hard-wearing, abrasion-resistant goat leather is used across the palm, including a reinforcement patch at the thumb-forefinger join.

Waterproofing and breathability

These mitts are pretty bombproof, with a sturdy, strong-feeling design that’s ready for the wettest and wildest of wintry conditions.

We were impressed with the waterproofing during our limited test hikes, but certainly more time is needed in atrocious conditions to truly evaluate their performance longevity.

Some online reviews suggest the goat leather palm can, over time, absorb water and make the gloves feel slightly colder, but I haven’t noticed this yet and I will report back in due course.

Waterproofing in these gloves comes courtesy not of Gore-Tex, but instead from that aforementioned 100% waterproof BD.dry insert. Black Diamond says it's "designed to keep you comfortable and moving in tough conditions".

The mitt shell also features Black Diamond’s innovative GTT Empel DWR (durable water repellent) treatment, which is billed as a "revolutionary PFC-free water repellent finish that is superior in performance and durability". This further helps to deflect and shed rain, with water beading nicely on the surface.

Black Diamond describes the eco-friendly innovation of Empel as follows: “Earth friendly, extremely durable, with unparalleled performance, GTT Empel breathable water protection uses a patented process to permanently hyper-fuse the water protective finish directly to the individual fibres of the fabric, offering unmatched super-hydrophobic properties, while maintaining optimal breathability.”

Breathability is decent, but in my view it’s quite easy to overheat in these super-warm gloves, so there’s a pretty good chance your hands will feel clammy if you use them in milder conditions.

Warmth and insulation

Mitts are generally warmer than gloves, and that’s certainly the case with the Mercury Mitts.

They're exceptionally warm and super-cosy, and will definitely be able to handle the coldest of wintry conditions in places like Scotland (some online customer reviews claim to have used these gloves comfortably down to -10°C).

All of this warmth comes courtesy of a thick wadding of 340gsm-grade PrimaLoft Gold insulation in the removable liner.

This version of PrimaLoft features Cross Core, one of the brand's high-tech innovations, fusing a NASA-developed aerogel with "normal" PrimaLoft fibres for "industry-leading performance", as PrimaLoft puts it.

On top of the PrimaLoft insulation, you also get a soft, high-loft fleece lining to the interior of the liner glove for extra cosiness.

It’s also worth noting that PrimaLoft’s synthetic, ultralight fibres - which are excellent at trapping warmth - retain most of their insulating properties even in damp conditions, so you can maintain comfort, warmth and thermo-regulation no matter what is happening with the weather.

Some extra warmth comes from the mitt design, too. The Mercury's internal space is roomy and allows the fingers to touch each other in the palm cavity, thus sharing and maximising body warmth around the hand.

There are no individual finger slots or sleeves, as some other mitts utilise. This approach prioritises warmth and is effective at doing so, but it severely reduces finger dexterity.

The drawback of all of this warmth is that the Black Diamond Mercury Mitts are probably overkill for milder conditions. In fact, for many UK outings they may prove too warm, but in countries that experience colder temperatures, the warmth will undoubtedly be welcome.

Fit, grip and dexterity

The Mercury Mitt is a mitt, not a five-fingered glove, with a standard mitt shape and design. The fit appears to be true to size and comfort levels are very high.

The cut of the mitt is quite spacious and roomy, with a large, rounded cavity for the hand. This cavity has no individual slots for your fingers. The outer of the mitt, again, is rounded with a rather blunt design.

All of this means that finger dexterity is rather poor here, although that’s generally to be expected with thickly-insulated mitts.

During my tests I found that any fiddly tasks requiring precise or nimble finger movement – such as fiddling with zippers on a waterproof jacket or using a foldable map – were not really possible in the Mercurys.

All-round dexterity performance was low, therefore, and I'd suggest Black Diamond has entirely prioritised warmth over dexterity with the Mercury Mitt. Some may prefer a better compromise between the two, but for others the added warmth will be welcomed.

In terms of grip, the Mercury Mitt performs better. The goat leather palm and additional reinforcement layer "stands up to rocky terrain, repeated rope handling and the general wear and tear associated with dedicated mountain use", according to Black Diamond.

For ice axe or trekking pole use I'd say the leather works well with good (but not exceptional) all-round traction.

The Mercury Mitt has pretty good (but not superb) adjustability overall. The insulated liner has no adjustability, so it either fits well or doesn’t. But for me it fitted fine.

The outer mitt shell, however, has a well-designed drawcord closure system at the base of each gauntlet (it’s also worth noting that the gauntlet extends deeply down the forearm, providing superb overall coverage).

The drawcord works very well and enables a fine-tuned closure to lock out the weather. However, there's no way to cinch-in or loosen the fit around the wrist, although the cut is elasticated at the wrist.

Weight and sizes

On my scales, the Black Diamond Mercury Mitt weighs 137g per glove (men’s medium), which is at the heavy end of the spectrum.

For comparison, the Mercury Mitt clocks in at 16g heavier per glove than the Rab Guide 2 GTX (small) and 29g heavier per glove than the Extremities Torres Peak (small).

For some users, this hefty weight will be a deal breaker and overkill for their activity preferences. But for others the heavy build will be reassuring – a sign this glove is bombproof and truly winter-ready.

Men’s size options range from XS to XL, while the women’s version is available in XXS to L.

You can figure out which size is right for you by measuring your palm’s diagonal circumference around the dominant hand at the knuckles with fingers together, and then your palm length from the crease at the base of your wrist (on the palm side) to the tip of your middle finger.

For example, the women’s small glove is suitable for hands with a 17.1-18.4cm palm circumference.

Features

On the top of each mitt you get a small loop of fabric, which facilitates hanging them open-side down for drying at home after a day in the mountains, while across the back of each thumb a softer, smoother fabric can be used to clean goggles or wipe your running nose.

You also get a clip for connecting the gloves together, and each glove has a very long gauntlet with excellent forearm coverage. It’s also worth noting that Black Diamond products come with a two-year warranty.

But you don’t get any of the following features with the Mercurys: touchscreen compatibility, any mechanism for cinching-in the fit around the wrist, or wrist leashes. The latter is a slightly disappointing omission.

Verdict

The Black Diamond Mercury Mitts brilliantly combine a removable PrimaLoft liner with a durable, stormproof mitt shell for top-notch warmth and comfort, but dexterity is poor.

For more warm-weather kit, take a look at our list of the best down jackets.

About the author

James Forrest is a prolific peak bagger and long-distance walker who’s one of the most high-profile outdoor writers in the UK. He writes regular features and route guides for Trail and has been one of our main gear testers for the last few years.

James is based on the edge of the Lake District so when he isn’t off on his latest crazy adventure or challenge, he’s walking in his local fells. James reviews every type of outdoor kit for Trail and is a real authority on everything you need for wild camping and packing light for a multi-day walk.

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