How I wash wool without ruining it
Wool is more forgiving than its reputation suggests. A basin of lukewarm water, a small amount of gentle wash, and a lot of patience will get most things clean.
Press the water through the fabric rather than rubbing. Rubbing and hot water are what cause felting, not the wool itself. Rinse in water of the same temperature, so the fibres are not shocked.
Lift the garment out supported from below, roll it in a towel to take out the moisture, and dry it flat. Hanging a wet sweater stretches it, and no amount of blocking will fully bring it back.