Billed as the world’s lightest waterproof jacket, the Berghaus VapourLight Hyper Smock tips the scales at just 94g in a medium and packs down into an apple-sized, highly-stowable package using its 5g stuff-sac.

Developed by the crack MtnHaus design team with Philippe Gatta, it’s aimed primarily and lightweight trail runners, adventure racers and anyone else who the lightest, smallest, but still waterproof shell they can get away with.

Tech Dump

The Hyper Smock actually started as a lightweight windproof using super-lightweight 7-denier Nylon fabric with an added PU smear to increase water resistance. It wasn’t until the prototypes got out there and used that Berghaus realised that the fabric was actually completely waterproof.

A whole bunch of head-scratching, testing – including a winning outing on the Spine Challenger race –  and experimentation with different sealing techniques eventually finished up with a fully-taped garment.

In tests waterproofing rates around 7,000mm, significantly less than something like Gore-Tex or eVent which will score 20,000mm+ but enough for normal use.

Performance

It’s all about the lightness. The fabric is filmy light, almost translucent in fact and Berghaus has shaved grammes wherever possible. That means minimal elasticated cuff, hem and tiny adjustable hood closures, just one miniature sleeve pocket for a key or a rolled-up tenner and a half-zip with storm flap.

The pocket’s on the sleeve rather than the chest like most, because Berghaus found it was less flappy there when there was something in it.

The cut is short-ish and quite snug though we could fit a Berghaus Hyper Therm underneath it if necessary and there was enough space for the broader than average editorial shoulders. Plenty of room for a beanie under the snug hood as well.

And the pack-size is impressively small. It’s around apple dimensioned and stuffs easily into a small stash pocket with or without the 5g stuff-bag supplied, And that’s vital because the raison d’être of the Hyper Smock is mostly to be carried around rather than used.

It’s brilliant for stuffing into a pack pocket, bum-bag, jersey pocket or similar on those ‘just in case’ days when it might or might not rain and you’re travelling light. Great for gramme-counting adventure racers too.

But what’s it like when you do actually have to use it? Surprisingly effective is the answer. It kept us – and OM contributor Nik Cook – protected from wind and rain for an hour or so at a stretch and while it’s not quite as breathable as top-end fabrics like Gore-Tex Active Shell or Polartec’s NeoShell, it’s actually not at all bad.

We also found we could roll up the cuffs for some extra fore-arm cooling when needed. The hood’s okay too, all-right, the ‘peak’ is super minimal, but mostly it does the important bit, which is covering your head.

We’ve found it if not ‘durable’ then not obviously tissue paper fragile either. We wouldn’t be wearing it regularly with a pack and climbing use would potentially trash it fast, but it’s no more obviously shreddable than a similar weight windproof top and for normal running and even road-biking use it’s been fine bar some minor fuzzing of the hood trim.

Like Nik, we’re not overly convinced by the tiny sleeve pocket, which is about business card sized and while the elasticated hem and drop-tail match the shapely editorial butt nicely, it may not quite suit everyone. Then again, adjustment would cost valuable grammes.

Verdict

The VapourLight Hyper Smock’s a narrowly focussed bolt of minimalist lightning for sure, but don’t make the mistake of thinking you lose out on waterproofing or breathability as a result, both are quite acceptable.

It’s not a shell you’d choose on days when you expect continuous rain or want ultimate protection – check out Berghaus’s Vapour Storm if that’s your bag – but if you’re after a waterproof top that can live in your pack or bum-bag unobtrusively until needed or you’re a gramme-slashing racer on a minimalist mission, there’s nothing out there to match it. And at £120, it’s not even insanely expensive.

Full Specification

• 7D Nylon  waterproof fabric with 7,000mm HH
• Adjustable hood
• Elasticated hem with drop tail
• Lycra-bound elasticated cuffs
• Underarm gusset
• Small sleeve pocket
• Half zip with storm flap