My daughter loves anything messy. She'll find the tiniest spot of mud in the grass and find a way to cover herself in it. So when I saw this flubber slime activity, I knew that the kids (and neighbors' kids) were in for a gooey-good time! Borax (sodium tetraborate) is a naturally-occurring mineral salt commonly used as a laundry booster or cleaner. As with any other cleaning product, it should be kept away from children not under direct supervision of an adult. Do not allow children to ingest Borax. If consumed, contact a poison control center immediately. Wash hands after play, as prolonged skin exposure may cause irritation.