"Eating through" can be used to describe something that is gradually corroding, deteriorating, or damaging a surface. The antonyms for "eating through" would be words that imply something that is slowly repairing, restoring or strengthening a surface. Some of the antonyms include words like "building up," "strengthening," "repairing," "fixing," "reinforcing," and "protecting." These words suggest the opposite of the damage that comes with "eating through," and imply the act of rebuilding and protecting a surface, rather than destructing it. It is important to remember that language is powerful, and using the right antonyms can be a more effective way to communicate your message.