pray4surf
Explorer
Propane will leave a sooty residue, one of the few downsides of a propane campfire IMO. I carry a brush to knock it off before I pack it up each time, if I do this it's not much of a job to keep it clean.
Propane is only going to leave a sooty residue if the air/fuel mixture is incorrect. Else, all of our propane stoves would leave us with sooty residue every time we cook.
Probably to enhance the 'fire pit' experience, i.e. yellow/orange flames, the fuel air mixture is set to rich... A blue flame is what one wants when burning gas.