I am an herbalist. You need to put lavender on IMMEDIATELY after the burn occurs or it won't stop the blistering. I have used it straight on any and all burns (especially from the curling iron) and have never EVER blistered. Keeping it on during the healing process will eliminate scars.
Here is the story of lavender. "Lavender oil and burn treatment have a long history. A French chemist Rene Maurice Gattefosse in the early 1900 was working in his lab and burned his hand severely. He then stuck his hand in a nearby container of lavender oil. He discovered his hand not only stopped hurting, it healed faster and didn't scar."