My acrylic paint has clumps and strings in it! What should I do?

Strings and clumps occur when the top layer of paint starts to dry. Air gets trapped in the top part of the bottle and
forms a skin. When you go to use it, it gets mixed back into the other liquid and causes clogs. Sometimes you might be able to remove the clumps if they haven't been mixed in with the rest of the paint. If the paint looks like chunks of rubber bands, it has frozen and thawed too many times. At this point, it is unusable.