Cleaning wool—especially deep pile material like this—can present a real challenge.
Wool. Raw wool. For those of us who live in colder climates—especially when our shelters do not have completely regulated temperature and humidity control—unprocessed wool is just the ticket for warm clothing, rugs, and blankets.
Raw wool—with its relatively high oil content—gives extra-good protection from cold, wind, and moisture. Its one real drawback is that it does seem to collect and hold more than its share of grime. You'll want to remove all that from time to time even if you're not deeply offended by dirt. A clean fabric, you know, lasts longer than one that's subjected to abrasion by ground-in particles of soil.
Cleaning wool presents problems, however, especially if the article is the size of a blanket or floor covering. The commercial method is costly, uses petroleum distillates, and may remove the fabric's oil content along with the dirt. Washing an 8' X 10' wool rug is almost out of the question, and beating carpets is an unpleasant job at best.
It's lucky, therefore, that the same cold weather which generates the need for woolen textiles often provides an effective means of cleaning them. This method costs nothing, taxes no resource other than a little of your energy, and cleanses large articles as efficiently, completely, and evenly as any home technique we've tried. Most important, it leaves the oil content of raw wool—or the remnants of oil in processed wool—virtually intact. The secret? Snow.
Cleaning is best done at a temperature of 25° F or colder, and on shaded new or powdered snow. Generally, the smaller the flakes the more complete the "washing" will be. Very fine, windblown powder several inches deep seems to work most effectively.
The article you want to clean—let's say it's a rug—should first be set outside in the cold air for half an hour or so. Why? Because  bits of grease that have collected on the fabric will harden and break up at temperatures below the freezing point, and  a chilled textile won't melt the cleansing snow (which would otherwise soak to the material and turn to ice).
When the rug is cold, spread it flat on clean snow and walk over its entire surface, trampling it into the white powder until the fine particles work their way through the weave. Then turn the carpet over, place it on a fresh area and repeat the process. Most of the dirt will come out in the course of this treatment, but you may want to cleanse the article a second time in the same way. Brush off any sow that clings to the fabric, and the work is done.
If you don't care to tramp around in the snow yourself, enlist a seven-year old child. Ours does an amazingly thorough job and has never yet failed to turn the business of cleaning wool rugs and blankets into a game of one sort or another.