The solution contains alcohol — does it sting on open skin, and are there any fire safety precautions?

The aqueous-alcohol base serves two purposes: it helps the brilliant green spread in a thin, even film and it evaporates rapidly, which is why the pencil feels dry within seconds. On intact skin the sensation is usually neutral; on a fresh cut or abrasion the alcohol typically causes a short, sharp sting that subsides as the liquid evaporates — this is expected and not a sign of damage. Because the product contains flammable alcohol, do not apply it near open flames, lit cigarettes, gas stoves, candles, or any ignition source. Wait until the treated spot is completely dry (usually under a minute) before approaching heat. Store the pencil at room temperature, away from direct sunlight and heat sources, and keep it out of reach of children. If the cap is left off and the tip dries out, the applicator will no longer deliver solution evenly; a tightly closed cap preserves both the alcohol content and the dye concentration for the product's shelf life.