What is a dirty sandchest?

A "dirty sandchest" typically refers to a type of chest or container filled with sand that is used in various contexts, often related to play areas for children or specific types of art projects. The term may imply that the sand within is mixed with debris or other materials, making it less clean for activities like sand play. It's important to ensure that any sand used in children's play areas is safe and free from harmful contaminants.