What other ways to wash a mattress from a sponge? For removing stubborn stains, baking soda is a good solution. Mix 2 tablespoons of baking soda with a small amount of water and apply this paste to the stain. After about 30 minutes, wipe the paste off with a cloth. Remember not to get the mattress too wet. Foam mattress should be washed dry, as wetting the sponge can damage the mattress. You can also dry-clean your mattress completely with baking soda. How to wash a foam mattress with soda? The method is simple: sprinkle the whole mattress with soda evenly and leave it for a few hours, or preferably overnight. After that time, vacuum the mattress thoroughly. To increase the effectiveness of cleaning the mattress from the sponge with soda, the cleaned action should be repeated with the other side of the mattress as well. Many furniture stores in dublin sell baking soda, because they know that it is good solution to clean your mattress.