In an effort to keep themselves groomed, cats will sharpen their claws on anything that can get the job done. Often this includes furniture, curtains, or some item we absolutely don't want coming into contact with a cat and its claws. One way to prevent this is to use double-sided tape on the legs and back of a sofa, on a curtain, or anyplace else the cat might contemplate using. The feel of the adhesive is repellent to cats, and once they touch it, they won't want to go near it again. Watch to see where the contact points for the cat are on a piece of furniture, and strategically place the tape on those spots.