DONE RIGHT, A GOOD MIDLAYER IS THE MISSING LINK IN HIGH ALTITUDE CLOTHING. WITH THE RIGHT SORT OF BASELAYER UNDER IT, A MIDLAYER SHOULD BE NEITHER TOO HOT OR TOO COOL, FORMING THE ‘ACTION LAYER’ THAT YOU WILL WEAR 90% OF THE TIME ASIDE FROM THE HEAT OF THE LOWER SLOPES, THAT YOU WILL SLEEP IN, AND THAT LETS YOU PUSH YOUR DOWN SUIT’S CAPABILITY A BIT FOR BAD CONDITIONS.
A GOOD MIDLAYER FITS WELL TO CREATE A THICK LAYER OF STABLE AIR THAT MOVES WITH YOU, SO NEEDS TO BE SUPPLE ENOUGH TO MINIMIZE DEAD AIR SPACES AND SMOOTH ENOUGH SO ANYTHING OVER IT DOESN’T RESTRICT IT. IT NEEDS A BALACLAVA-STYLE HOOD TO ACT ALMOST LIKE A DRYSUIT – TO CREATE A GASKET SO WARM AIR DOESN’T LEAK OUT. A GOOD MIDLAYER NEEDS TO ALSO WORK AS A MOISTURE SHIELD, BOTH REPELLING PRECIPITATION AND STAYING WARM AGAINST SWEAT.
TO WORK UNDER A DOWN SUIT THE MIDLAYER NEEDS TO BE STREAMLINED, ALMOST LIKE A BASELAYER, TO NOT ADD BULK AND GIRTH TO THE ENSEMBLE EVEN THOUGH IT NEEDS TO SIT BELOW HARNESS LEVEL. IT NEEDS TO BE LIGHT AND IT NEEDS TO BE DURABLE, TO NOT LOSE IT’S THERMAL PROPERTIES FROM BEING LIVED IN FOR DAYS AT A TIME.
DOWN IS OUT BECAUSE IT’S TOO EASILY COMPROMISED BY MOISTURE AND COMPRESSED BY SLEEPING IN. FLEECE IS OUT BECAUSE IT’S TOO BULKY AND SOAKS UP MOISTURE. HIGH LOFT, LOW MASS KNITS LIKE ALPHA ARE OUT BECAUSE THEY DON’T WORK AS A GASKET OR STRETCH WELL. REGULAR SYNTHETIC IS OUT BECAUSE IT’S BULKY AND DOESN’T BREATH WELL.
EFFECTIVELY THE ONLY STUFF THAT TICKS ALL THE BOXES IS THE NEWISH STUFF FROM PRIMALOFT – THERMOPLUME.
MONTANE HAS HARNESSED THERMOPLUME’S PROPERTIES REALLY WELL BY MAKING FORM-FITTING LAYERS THAT ARE BARELY AFFECTED BY MOISTURE, HAVE THE FEEL OF DOWN, BREATHE WELL AND SIMILAR THERMAL PROPERTIES TO ABOUT 650 LOFT DOWN. WARMER JACKETS EXIST, BUT FOR THE JOB OF UNDER A DOWN SUIT THE ‘LITE’ VERSION HITS THE SWEET SPOT – ANY WARMER AND IT WOULD BE TOO MUCH LOWER DOWN WHERE THE SUN STILL HITS.
AS IS, THE ICARUS LITE WORKS ALMOST AS A SHELL WITH THE THERMOPLUME SHIELDING LIGHT PRECIPITATION YET STILL BREATHING WELL. UNDER A SHELL JACKET FOR MORE SERIOUS WIND AND CONDITIONS, THE THERMOPLUME MAINTAINS A WARM AIR LAYER THAT DOESN’T COMPRESS OR LOSE EFFICACY LIKE DOWN WILL.
WE LIKE THE SIMPLICITY OF THE JACKET TOO, ACTING LIKE A TRUE MIDLAYER SO STRIPPED OF MOST FULL OUTER JACKET DETAILS TO LEAVE SOMETHING THAT’S LIGHT & COMPACT FOR LOWER DOWN BEFORE IT’S NEEDED THEN STREAMLINED FOR THE REST OF THE TIME WHEN IT IS WITH JUST ENOUGH POCKET SPACE FOR THE ALWAYS-CARRIED HEAD TORCH, LIGHTER & THIN GLOVES.
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