How can I treat straightener burn on arm?

Care for wound. Keep the wound clean and apply a topical antibiotic ointment (e.g., polysporin, (bacitracin and polymyxin) bacitracin, neosporin, triple-antibiotic ointment). Also be sure to get good nutrition so that you have all the necessary building blocks for wound healing. If the wound seems to get infected or is not healing, seek medical attention.