Always save at least one label from your yarn when you make an item that needs to be washed often. Keep it where you can easily find it when it's time to wash the piece. Some yarns can be safely washed in the washing machine and dried in the dryer, but others would be destroyed by such treatment. If you have any doubt, play it safe -- hand-wash it.
Fill a sink with lukewarm water (never hot!), and add a small amount of mild soap made especially for delicate knits. Put the garment in the sink, and allow it to soak. Do not agitate or handle roughly, or felting could begin. Drain the sink, and gently press down on the garment to squeeze some of the water out. Never wring or twist a wet item; always support the weight so the item doesn't stretch. Fill the sink with cool rinse water; allow the item to soak, drain the water, and again gently press out the excess water. Repeat until the soap is removed.
Have a blocking board (a thick, padded board on which to pin damp garments so they can dry to the correct size) ready, or spread a layer of thick towels on a flat surface such as a table or a bed. (Never hang a knitted garment.) Lift the garment from the sink with both hands without stretching it, and spread it out on the prepared surface. Use a tape measure to shape it to the correct measurements. Pin in place using rustproof T-pins, and let dry.
Some yarns, including wool, can be blocked by using steam, but always check the yarn label first. Lay the garment on a blocking board, and pin it to the correct measurements. Keep the steam spray several inches above the garment -- never put it directly on to the garment.
Sometimes you wash a knitted piece in order to felt it. Learn about felting on the next page.