When using lead, NEVER SAND LEAD, FILE ONLY! Wear proper respiratory protection. When melted, the temperature should be kept as low as possible.The respirator should have a HEPA (high efficiency particulate air) filter, also known as a N100 filter. Where airborne exposures may exceed OSHA/ ACGIH permissible air concentrations, the min. respiratory protection recommended is a negative pressure air purifying respirator w/cartridges that are NIOSH/MSHA approved against dust, fumes & mists having a TWA not less than 0/05 MG/CU M. Always follow all instructions and warnings and wear proper eye, ear, skin and respiratory protection. When using chemicals always consult MSDS and product data sheets for proper safety precautions.