In part 1 of this comprehensive two-stage article Matt Fuller, Dr. Matthew Morrissey and Dr Mark Taylor discussed the science of insulation and staying warm. Here in part 2 they present a brief history of insulated clothing and equipment, weigh the pros and cons of down vs synthetic, describe testing methods, and offer some interesting ideas for future garment technology.
In reply to UKC Articles: The bit about down fill power testing is wrong, at least if what Mountain Equipment is saying is correct. This is from the latest ME technical work book:
"Over the past forty to fifty years various methods have been developed to measure fill. Contrary to popular myth there is now only one single recommended test for fill-power performance. The days of having to question whether down has been tested to US, EU or EN standards or making ad-hoc and often inaccurate calculations to try and convert numbers between manufacturers should be a thing of the past. There is now only one internationally (IDFB) recommended test – the Lorch Cylinder Test and one recommended preconditioning method - steam.
Mountain Equipment was an early adopter of this revised standard and for the past five years all our testing has been done according to this method. In addition to that we have consistently chosen to advertise guaranteed minimum standards of fill power performance. Following a 3 year period of achieving consistently well-above advertised performances with the down we source we are now amending our advertised fill-power ratings so that they better reflect the quality of the product you are actually buying." (p.13)
Toby, you raise a good point, and it's something I very briefly discussed with Richard Talbot at ME, though we never reached a conclusion. ME are right that the only conditioning method currently recommended by the IDFL is the steaming method as it is fast, repeatable and gives 'big numbers' (it is the Official IDFB Method). Basically everyone reports numbers based on steam conditioning, though there are numerous other conditioning methods that may still be used. However, the other testing factor is the cylinder. The EN and the US cylinder differ very slightly in diameter, and the weight and subsequent pressure applied to the down. I have read through the IDFL's articles (www.idfl.com/info/articles/) and can't find mention of there being a specific cylinder to use. The lorch machine is used by many manufacturers but as far as I know is not the definitive testing machine. I will contact the IDFL for a bit of clarity on the issue and post up their response.
In reply to TobyA: I got a reply back from the IDFL and they make it fairly clear that steaming is the recommended conditioning method, but there are numerous alternative cylinder methods, still. The IDFB recommend certain specifications on the cylinder and fill weight, though companies are free to use alternative methods, such as the EN, Japanese, or USA method. Thus, it would seem the problems of converting between different fill powers remains.