After a finger is scalded, the high local temperature causes some damage underneath the skin, resulting in the skin oozing fluid. This fluid accumulates and forms blisters, so after a scald, the finger may develop a blister or several blisters. Once a blister has formed, try not to puncture it. It can be disinfected with iodine and allowed to absorb slowly on its own. Puncturing the blister might lead to infection, worsening the condition. Generally, after a finger is scalded and a blister forms, it suffices to disinfect the area. Of course, it is crucial to cool the finger quickly after the scald to minimize further damage.