If you let the fire wicks smolder by allowing all the fuel to be used up then the KEVLAR wick will burn away slowly and fall apart. Sunlight also degrades and darkens the color of KEVLAR wick slowly over time. So it is good to have wick covers when using Fire Props during daylight, it also stops you from getting your daytime clothes dirty from the residues on the wicks. Many people wrap some tin foil over the wicks and then put some colorful socks over that. We also sell some fluffy covers which can fit over some common KEVLAR Fire Heads.