Why is soot on my gas fireplace logs after burning?

Similar to a wood burning fire, a vented gas fireplace system is less efficient, produces less heat, and creates more soot. Vented systems are designed to burn with a yellow-orange flame that closely resembles a wood fire. Soot build-up is a normal part of the combustion process and usually adds to the realism of your log set. Liquid Propane log sets generally produce more soot than natural gas log sets. Sooting is not normal on vent-free gas log systems commonly found inside the home. If desired, soot may be removed by lightly brushing the logs with a soft-bristled paint brush. Soap and water may be used for additional cleaning. Do not use abrasive cleaners as they may remove the log coloring or chip the bark details. Do not attempt to clean while the log set is hot.