Tempur-Pedic sells many of their mattress toppers with machine-washable covers, but sometimes liquids such as urine soak through the cover and into the memory foam. Because Tempur materials, as well as any type of memory foam, deteriorate when exposed to excess moisture, machine-washing the fabric cover and drying the memory foam topper before treating it with baking soda is typically the best method for removing urine odors and stains. If you're comfortable, you can also use a small amount of diluted white distilled vinegar.
Soak up standing urine on the mattress cover with an absorbent towel. Unzip the cover and take it off the Tempur-Pedic mattress topper. Move just the cover to the tub or sink temporarily.
Remove the topper from the bed, if applicable, and place it on a flat work surface. Gather several absorbent towels. Using a dabbing motion, absorb as much of the urine as possible from the memory foam, working until the towel comes up dry. Replace the towel as necessary.
Fill a spray bottle with equal parts warm water and white distilled vinegar. Lightly spray only the stained area of the memory foam; do not saturate the material.
Flip the memory foam over and spray the opposite side of the stain. This allows you to evenly treat the urine spot without apply too much vinegar to one side of the topper.
Wait 5 to 10 minutes and then blot the vinegar off the mattress topper with clean towels. Smell the topper; if the scent is still present, repeat the process again. It is best to apply a small amount of the vinegar solution in several treatments rather than saturating the topper with one treatment. The latter method runs the risk of breaking down the memory foam and permanently damaging it.
Set the mattress topper outside in a sunny location to dry, or lay it flat indoors. The sun has a natural bleaching effect on fabrics and materials, and it will help to minimize the stain.
Rinse the cover in cold water in the tub or sink, eliminating as much urine as possible while the memory foam dries. Lightly spray the stained part of the cover with a laundry stain remover.
Set your washing machine to the cold water setting and delicate cycle. Add laundry detergent, wash the cover and hang it on a clothesline, over a chair or flat on a table to dry. If desired, set the cover in a sunny location to further eliminate the stain.
Bring the topper indoors once it's completely dry. Generously sprinkle baking soda over the mattress topper. Let it sit for 24 hours and then vacuum it thoroughly.
Reinstall the cover on the mattress topper only when both are completely dry.