Mammut Jacket Changes With Climate

New for this spring 2009 from Swiss brand Mammut is a jacket using a membrane-based fabric that becomes more or less breathable depending on temperature.

The Exteme Cho Oyu Jacket is a lightweight, supple alpine waterproof hard shell that uses Schoeller's c_change membrane, which, says Mammut 'opens and closes like a pinecone according to the ambient temperature. At a temperature increase from 10C to 20C, moisture vapour transfer rates or breathability increase by about 50 per-cent. In the reverse situation, the structure of the polymer contracts and increases the heat retention properties of the fabric.

Schoeller call the fabric 'The Bionic Climate Membrane' and it even has its own web site: www.c-change.ch


When it's warm or high levels of activity generate heat inside the jacket, the structure of the membrane opens up to improve moisture vapour transfer to the outside. Conversely, when things are cooler, the membrane closes down to conserve heat around the body.

All of which may sound improbable, but bear in mind that when eVent first appeared, the increased breathability meant that some testers found the fabric felt less cooler than similar materials because water vapour could escape more easily taking heat with it.

In lab tests, the fabric is highly breathable. Mammut claims MVT - moisture vapour transfer - rates of 20,000 g/m2/24h, which, while lab results are only part of the story, is roughly comparable to eVent, which is the most breathable conventional waterproof fabric we've used.

The jacket itself is a lighweight alpine design with a close tailored fit, high reach sleeves, M.A.P hood, under-arm ventilation and more. Looks good too, in a continental sort of way. So what's the snag? Er, the Cho Oyu has a suggested retail price of £370, so you'll need a fairly substantial wallet to go with it.

More Mammut stuff at www.mammutsportsgroup.ch