There's no need to cry -- or cuss -- over spilled milk. A spill on your favorite upholstered furniture doesn't have to turn into a stinky, curdled mess. Remove the milk by diluting it or scraping away dried residue, washing the area with a mild soap, then preventing sour-milk smell with natural odor-removing substances. The sooner you treat the milk spill, the easier it is to clean up, and the less likely it will smell sour, whether the upholstery is leather, pleather or a woven material.
Blot the Spot
If the milk spill is fresh, quickly grab paper towels or absorbent white cloths such as towels, blotting the spill to absorb as much liquid as possible. If the spill is on a fabric couch or chair cushion with a zipper, unzip the cushion and place a dry towel or stack of paper towels between the upholstery and the foam to catch any liquid that soaks through. After blotting as much milk as possible, wipe the area with a damp white cloth, followed by another dry cloth to absorb excess moisture. Be sure to check between cushions and other places the milk may have dripped; otherwise, it may dry and stink later.
Dealing With Dried Milk
If the milk is already dry, you'll have to remove some of the dried matter before cleaning it with a wet solution; otherwise, wetting the area may rehydrate the milk enough that it soaks into the upholstery even more. Keep a trash bag or sheet of newspaper nearby; then pick at the dried milk with your fingernails or the edge of a plastic spoon or plastic spatula. Do your best to scrape just the milk instead of abrading the upholstery as well, which could damage the fibers or the texture of the upholstery fabric. Knock the dried milk flakes into the trash can or atop the paper; then empty the collected flakes into the trash.
Wash It Away
Add a squirt or two of a gentle dishwashing liquid to a cup of cool water, swishing the liquid around to stir in the soap. Dip a sponge or a white lint-free cloth into the soapy water, wringing out much of the moisture. Dab, blot and wipe the affected area, wiping from the outer edges of the milk toward the center of the spill to prevent spreading the milk through more of the fabric's fibers. Rinse the sponge or cloth out frequently, as it may absorb some of the milk as you clean -- if so, you'll see the water running white into the drain. Continue blotting with the soapy water until the milk is gone; then rinse the cloth and wipe the area once again. Pat the area dry with a fresh absorbent cloth.
Milk Odor Removal
On any type of woven or porous upholstery, the fabric may develop a sour milk smell, even if the upholstery smells fine after cleaning it with soap and water. Sprinkle baking soda over the affected area -- whether the upholstery is wet and clean or dry and stinky -- and allow the baking soda to sit overnight. Baking soda absorbs odors trapped in fabric, much as it does in the refrigerator. Brush off or vacuum up the baking soda the following day. If vacuuming, use an upholstery brush attachment to help protect the fabric.