There is a lot of new insulation in the market today. Water resistant down. Polartec Alpha. Some new PrimaLoft Insulation. All these new developments provide excellent cool and cold weather choices for product users and product developers. I am not going to get into specifics on the insulation but rather review how to best use some of these new developments.
Insulation works best if held in place and if it provides sufficient loft to hold dead air space. Air proves to be an excellent insulator, but it can’t be moving around. That’s what insulation does – it traps air and uses it to keep you warm.
The challenge has always been twofold 1) how to hold it in place so it provides the necessary dead air space and 2) migration. Down insulation uses baffles to hold the down in place – rectangular or box is pretty standard, trapezoidal is better as it eliminates a vertical cold seam. Synthetic insulation can be sewn into place. This holds the sheets of insulation between the outer shell fabric and the inner liner. Here again you have the problem of a seam pinching the insulation and causing a cold spot. Seams can be offset or spread apart enough to reduce the impact of these cold spots.
The second issue is migration. Migration occurs when the down or synthetic insulation pokes through the fabric and can be pulled out. To reduce this apparel manufacturers have used coated fabrics for the shell and liner to provide more resistance so that the insulation stays in place. The big trade-off here is that the coating on the fabrics reduces breathability. Use of two coated textiles – the lining and the shell – really provides a barrier to moisture trying to get out. This is particularly apparent under a high metabolic rate – sweat can’t get through the insulated garment fast enough. The result is damp insulation (which does not work as well) and a wet base layer.
Recently Polartec launched a new insulation called Alpha that addresses this issue by eliminating the need for coatings on the inside of fabrics. Alpha does not migrate through materials. It can even be used with a knit fabric like a softshell that would be disastrous to use with down. This is a very cool development. However, the user must be cautious about using Alpha as a replacement for down or traditional synthetic insulations. Alpha is something different because it is not going to be as warm due to its lower loft profile. Polartec is producing heavier weight versions but it is still not as warm as traditional synthetics.
It is best used for its superb breathability and low profile. When placed under the arms and in other high sweat producing areas as a replacement for traditional insulation it can dramatically enhance the performance of a loft product. Many brands have come out with jackets made completely of Alpha. These are great aerobic pieces but may not be warm enough to replace an existing low loft piece. As always, test and confirm the suitability of any new product in the field.
PrimaLoft has some new insulation that is also non-migratory. It is different from Alpha in that it is more like traditional synthetic insulation in its loft characteristics and thus should provide excellent warmth due to its loft as well as excellent breathability as a result of not needing coated fabrics.These are all excellent choices and appropriate combinations of these and other materials should result in some versatile garments with light weight warmth, low bulk and excellent breathability.