Use an open flame such as a propane torch. Keep the flame moving back and forth across the branding iron. Do not leave the flame in one spot over the branding iron. Watch the color of the branding head: when the color starts to change, make a test brand on a scrap piece of material. If the mark is too light, go back and heat it longer. If the test mark is too dark and creates more than a wisp of smoke, let it cool down for a few seconds and make another test mark before attempting to brand the final product. Let the heat do the work. Use only slight pressure, rocking the branding iron (without lifting it) forward to back and left to right.