Pour water into a galvanized steel bucket until it is half full. Use a bucket large enough to accommodate the amount of wash you are making. For example, if you are painting a wooden chair, you can use a much smaller bucket than if you are painting a dresser. Find these buckets at hardware or feed supply stores.
Add mason's lime to the mixture while stirring continuously until the solution is 3 inches from the top of the bucket. This gives the water and lime almost equal proportions, with slightly more water than lime. The exact measurements are not necessary since you will gauge the consistency and make amendments later.
Leave the mixture to sit overnight.
Pour the water off the top, leaving 1 inch on top of the lime. This lime will have settled on the bottom. Discard the water.
Mix 2 cups salt to 1 gallon of water. Pour this into the mixture, stirring constantly. Continue mixing the saline solution and adding it to the lime until the product looks like thin pancake batter.
Blend 1 cup powdered milk in 2 cups water to form a thin solution. Stir it into the lime mixture. This helps keep the lime from sticking to the container.
Paint the furniture with the mixture, using a bristle paintbrush.