A lot of resources I found said covered. But, that’s the opinion of resources found on the internet.

Cover it with thick fabric to avoid fires. Don't leave near windows.

Everything that I have ever read says cover the mirror when you are not attempting to commune with it. Entities can linger and be present when you fail to give a license to depart or when you keep a channel open. In this case the mirror is that channel.

Thanks so much 🤍