There are many lubricants marketed to the piano technology field. Some are safe and helpful, others should be used cautiously, and several should be avoided altogether. Lubrication should be considered an enhancement - not a repair. Proper lubrication can enhance the responsiveness of the instrument when parts are already operating freely and within tolerances.
Do No Harm: Lubrication Edition
Updated: Dec 15, 2023
I don't know of any health reason to avoid graphite except for excessive amounts of powered graphite which could cause lung silicosis. The DAG graphite that is commonly used is not a particulate and should pose no health hazard, aside from hypochondria and paranoia. The major reason I avoid graphite is because of the danger of spills or contamination of customer carpets.