There is constant heated debate about advantages and disadvantages of down and synthetic fibres, and there are as many opinions and favours as campers.
The advantage of down as insulation material is its insulating capacity in relation to weight. Down also packs into smaller space than synthetic fibres, and this becomes more important feature as we move on to thicker products. Earlier, the disadvantage of down was the fact that its insulating capacity weakened when it got humid, but nowadays many manufacturers treat the down in a way that increases the water repellency considerably.
When choosing down products, it is also good to take ethicality of down into consideration.
Over the last few years manufacturers, one after the other, have brought up themes of animal welfare. Down can be produced meaningfully as a by-product of meat production which of course also includes some issues in the sense of animal welfare. At least Responsible Down Standard (RSD) and Advanced Global Traceable Down certificates are “labels” which prove that birds have not been plucked alive or force-fed – on the contrary, special attention has been paid to animal’s wellbeing.
The advantage of synthetic fibres is that they do not need any special treatments but stay airy without them even when humid. Besides, products made with synthetic fibres are often cheaper than the ones made with down.
Products made of synthetic fibres, for example fibre products sold under tradenames Polartec and Primaloft are completely vegan as far as filling is concerned. PETA has published a list on safe vegan down alternatives (fillings)
There is variation in both material categories.
There is down of different qualities and it is measured with a special cuin or fillpower value. In general, you can say that when the value exceeds 600, the filling is of very high quality. The higher the value, the better the down’s insulating capacity in relation to its volume.
There are differences between different synthetic fibres, too. They affect the weight, packability and insulating capacity of the product. For example, a fibre of a lower quality becomes flat after a while and will not be back to airy and insulating again. So, invest in a high-quality fibre filling.
Other filling materials
Filling materials are constantly being developed, and they are amazing curiosities. We have seen wool fibres and all sorts of nettle pulp inside jackets. The chemical pulp fibre industry is going forward at a great pace. As far as we know, there is not yet a modern filling made of renewable natural materials in mass production. The problem is usually that even though good fillings have been successfully developed, they are no match for advanced materials currently on the market as far as lightness, packability, insulation, and water repellency are concerned. It is however an interesting genre, and it would be quite cool to be able to update this article with the advantages of natural fibre fillings in my lifetime.