WHAT IS DOWN
“DOWN” is a pure, natural, thermal-insulation product. It is grown by birds and in cold climates it enables them to survive severe weather conditions. The best down, therefore, is to be found on birds which spend winters in arctic or sub-arctic conditions.
Down is unlike normal feathers in that it grows without a hard, central “stalk” or quill. In mature birds it forms a soft, fluffy underlayer close to the body beneath the bird’s main feathers.
The most common sources of down are ducks and geese. Down is used as an insulating material in various man-made products such as sleeping bags, insulated jackets, and bed coverings.
In such applications the “down” insulation that is used is never 100% pure down but is a “down mixture” containing a small percentage of fine feathers also. This mixture is represented numerically as a ratio – for example 85:15, which means 85% pure down and 15% feathers. The greater the pure down % the better the insulation value, in theory, as long as you compare like-for-like qualities. In practice, above a 90:10 ratio it is quality differences which are of more significance in determining how good the insulation is. Quality is indicated by “FILL POWER” which is a measure of the down’s ability to LOFT – please see below.
Criterion sleeping bags contain a 92:8 ratio of pure down to feathers (small, fine feathers only) in our Criterion Ultralight, Criterion Lady and Criterion Traveller models. Our up-market Criterion Prime, Criterion Expedition and Criterion Quantum models are insulated with 95:5 ‘diamond grade’ Polish goose down.
Goose down is better than duck down, and POLISH GOOSE DOWN is recognised world-wide as being of THE highest quality. In particular it is beloved of the Japanese who are well known for demanding top quality and who buy large quantities of Polish down each year. The excellent quality of Polish down is partly due to climatic conditions, but is also the result of extensive academic research into breeding techniques, which are unsurpassed anywhere.
Criterion sleeping bags contain only Polish goose down, whose source is the non-polluted region of forests, lakes and beautiful, natural landscapes of North-Eastern Poland. This is a particularly cold part of Poland, suffering long winter weeks of arctic air with temperatures reaching as low as -36°C in January 2003. It is to combat such severe conditions that the geese, whose natural habitat has been this region for thousands of years, have evolved their protective down to a quality which is unmatched anywhere, both for heat retention and for durability.
Polish goose down is available in several qualities, as measured by its ability to LOFT (see below). Criterion sleeping bags incorporate the two HIGHEST qualities of Polish goose down. The higher the quality, the LESS WEIGHT of down is needed to achieve the required temperature rating for the sleeping bag. Hence high quality down means a lighter weight sleeping bag.
Criterion sleeping bags outperform competitive sleeping bags by their warmth to weight rating.
The down used by Criterion is certified by DownPass. To find out more about ethical certification read our down policy.
PERFORMANCE CHARACTERISTICS OF DOWN INSULATION
LOFT is the ability of an insulation material to take in air and expand. It is the trapped air which is the actual insulator. The “insulating material” is merely the means for trapping the air and preventing air movement. The greater the amount of air trapped in the sleeping bag, the warmer is the sleeping bag because it retains more of your body heat.
FILL POWER is a measure of the LOFT or expansion ability of down insulation. It denotes the volume (in cubic inches) to which 30 grams of down will expand when it takes in air. The greater the FILL POWER, the greater the expansion, the warmer the sleeping bag. (All other things being equal)
TYPICAL PERFORMANCE FIGURES (FILL POWER) FOR DOWN USED IN SLEEPING BAGS
| cu in | |
| duck down | 550 |
| Chinese goose down | 600 |
| Hungarian goose down | 660 |
| Polish Standard goose down | 700 |
| Polish Super goose down (white) | 800+ |
Criterion Polish goose down has been tested and certified by the International Down & Feather Testing Laboratory, Salt Lake City, Utah, USA to a MINIMUM rating of 680 cu in and 800 cu in respectively. Our newest ‘diamond grade’ white down scored 850 cu in, after steam conditioning.
LOFT ABILITY OF PARTICULAR SLEEPING BAGS
FILL VOLUME is a measure of how much the TOTAL of all the down in a particular sleeping bag will expand. The greater the FILL VOLUME, the warmer the sleeping bag.
The ability to loft of a sleeping bag depends on the weight of down that it contains and on the fill power or quality of the down being used. A comparison between sleeping bags can be done using the equation :
(weight of down in grams) divided by 30, multiplied by the fill power
For example, compare a sleeping bag filled with 900 gms of Chinese down, with one filled with 700 gms of Polish, diamond grade goose down.
| fill power | weight of down (gms) | TOTAL FILL VOLUME | |
| Using Chinese Down | 600 | 900 | 18000 |
| Using Polish Diamond Grade Down | 850 | 700 | 19833 |
Here the lighter sleeping bag is actually warmer than the heavier one since it has a higher overall Fill Volume.
When comparing the temperature or “season” ratings quoted by different manufacturers it is worthwhile doing the above type of calculation and comparing Fill Volumes.
The so-called “minimum comfort temperature” that is quoted by most sleeping bag manufacturers is supposed to be a measure of the suitability of a particular sleeping bag for use in cold conditions. However, it is a very subjective measure (different people can tolerate different levels of cold), and furthermore, there is no “standard” to which every manufacturer adheres. Sometimes these ratings are overstated to make particular sleeping bags appear more attractive, hence such information should be treated only as a rough guide. The above FILL VOLUME equation is a measure of a sleeping bag’s ABILITY TO LOFT and is, therefore, a useful tool for cross-checking such information when comparing several different sleeping bags.
However, it should be borne in mind that good design also has an effect and, for example, a sleeping bag which utilises a Trapezoidal baffle construction will have a comfort temperature rating of 2 to 3 °C lower (better) than a sleeping bag containing exactly the same quality and weight of down, but constructed using the Boxwall method.
Other constructional design features also have an effect. The better the overall design the lower the risk of “cold spots” arising when a sleeping bag is being used.
Technical Note – temperature ratings and overall weight
1. The effectiveness of insulation materials is affected by moisture. You will feel colder in your sleeping bag in high humidity conditions. Moisture will also add to the weight of a sleeping bag.
2. How warm you feel is also dependent on where you are sleeping. The size of the body of air surrounding the sleeping bag and the amount of air movement/ventilation both affect heat retention.
The comfort temperatures that we quote for Criterion sleeping bags assume that they are being used in average humidity conditions inside typically-sized 1 to 3 person tents (with a relatively small body of still air surrounding the sleeping bag). Use them in a drafty, unheated mountain hut in damp conditions and you will feel significantly colder.
That said, independent tests, carried out on our models in compliance with British Standard BS4745 and ISO 5087-1, gave temperature performance figures that are as good as or better than we claim.
DOWN versus SYNTHETIC INSULATION
Down is a better insulator than the best synthetic materials, “weight-for-weight”. It is lightweight with excellent loft yet is extremely compressible to give a small pack size. Down has excellent “drape” properties, settling around the body and eliminating the drafty gaps sometimes left by stiffer synthetics. However, down is a poor performer when wet, unlike some polyester fibres which resist moisture well. “Synthetics” are generally heavier and bulkier and with a much shorter life-span than down. Down’s greatest advantage, however, is its versatility as regards temperature conditions. Down sleeping bags have a wider spread of comfort temperature than synthetics, For example, a down sleeping bag with a comfort temperature rating of -15°C will still be comfortable when used at 0°C, whereas a synthetic sleeping bag rated at only -7°C could be too warm at 0°C. Anyone planning to use a sleeping bag at different times of the year in a variety of temperature conditions should consider using a down sleeping bag first and foremost.