In one sentence, describe what the following article is about:

When substances build up around the teeth of your zipper, it can prevent the zipper from staying closed. As a result, you’ll need to clean the teeth and remove stuff that could be preventing the zipper from closing.  Combine water and soap in a small dish, and stir until suds form. Dip a clean rag in the soapy water and wipe down the zipper’s teeth. Grab a fresh rag and run it under the tap. Wipe the soapy mixture off the teeth with the damp rag. Attempt to zip and unzip as normal.

Summary:
Remove buildup from a zipper’s teeth.