Hi. my son has a skin avulsion and the er doctor applied a liquid bonding type material on it. should i keep it covered with a bandaid?

Won't hurt: A loose fitting band aide would not hurt. Follow-up with his PCP to assure it is healing well after your ER visit. Best wishes.

Don't have to: If cosmetically unappealing spot, can keep covered, otherwise nothing wrong with leaving it uncovered. The cyanoacrylate glue will provide basic protection for the wound, but is a bit brittle, so avoid impact for at least 2-3 days. NO oil-based topicals or will dissolve the glue and open wound (best to avoid any topicals until after the glue has released and flaked off (usually 5-7 days).