A good paint brush is important to a good paint job so it is important to take care of them. Cleaning a paint brush takes time and a lot of water or thinner. Amateur painters are sometimes tempted to just drop the paint brush into a container of water or thinner to store it for a short time such as between coats or during a break. This practice damages the brush by bending and softening the bristles.
Determine if your paint is latex or oil based. You can save both time and water by this method of storing your paint brushes between painting sessions. This method is for latex paint only.
Place the wet paint brush in a large zipper type freezer bag and seal it up. Just to be on the safe side place that bag inside another bag, such as a used plastic or paper shopping bag for double protection.
Place the bag containing the paint brush inside the freezer. This will prevent the paint from hardening and your brush will be ready for use after thawing out in a couple of hours. You can keep wet paint brushes for weeks in this manner. Don't use this method for oil based paint since the fumes will contaminate your food in the freezer.