Most peacoats are made of wool or a wool blend. This makes them last longer and warmer, but it also makes them more difficult to care for if damages occur. Some companies now make peacoats out of materials that can be washed in the washing machine, which makes them slightly easier to care for. However, you can make your black peacoat look like new again with a little work, even if it is made out of wool.
Hang your coat on a hanger and use a garment brush to brush off any dirt or debris on the coat. Use a lint brush to remove any lint or pet hair from your jacket. If your jacket is stained, blot the stain with water and a stain remover meant for use with wool. Do not rub, as this can damage the wool.
Hand wash your peacoat very carefully in cold water with laundry detergent that is safe for wool if your coat still looks dirty. Do not use hot water and do not wring out or agitate your wool coat while it's in the water. Do not put your coat in the dryer or hang it up to dry. Lay it flat. A safer option is to dry clean your wool peacoat.
Use a needle and black thread to repair any seams, which are coming apart, or any buttons that are coming off. If you have lost buttons, consider replacing all of the buttons with new, matching buttons. Trim any loose threads.
Dye your coat with black dye if the color of your black peacoat has faded. Use warm -- not hot -- water with a wool coat. Do not agitate the coat. Lay flat to dry, turning the coat over from time to time to speed up the drying process, which may take a few days.
If you do not have a lint brush, you can wrap masking tape or duct tape around your hand a few times. The lint will stick to the tape when you rub your tape-wrapped hand against the coat. Some types of dye can be painted onto a coat and don't require you to soak the coat in warm water. This may be a good option. Wrapping your coat in plastic after it is dyed, and putting it out in the sun can help set the dye without risking the shrinkage that may happen if you use hot water to set the dye.
If you combine a wool coat with water, heat and agitation, the coat may shrink and felt.