Have open gash about 1.5cm long on face. Don't think need stitches. Keep it moist with Vaseline until body heals, or let it dry and scab over quickly?

Need more info. How deep is the wound.? How old is the wound? Where is it located? Must keep the wound clean. To minimize visible scarring need to see a doctor to see if it can be closed with fine sutures or surgical glue. If it is more than 24-48 hrs old then may have to allow to close on its own. Keeping it clean is very imporant.