Absorbs is the issue in talcum. I’ve never seen anyone use cornstarch. I would’t use it.. I don’t keep my belts in a bag with powder.
I clean the belts with warm soapy water. I rinse them in hot tap water and turn them inside out and put them on the right size jar. I let them dry and spray them with silicone spray and let them dry a second time. I remove them from the jar and flip them the correct direction and in a dry new bag they go.. NO POWDER!!
Before I install a treated belt I put it in a talkum dust bag. I powder it. Take it out of the bag with your (powdered) nitril gloves on and drop it on a paper towel a couple of times. Drop it on the narrow side of the belt a couple of times..
It’s ready to install. DON’T breath the powder or any powder for that matter.
Clean all the pully surfaces with alcohol. Clean and service the platter bearing at the same time.. Same with the motor. Clean, oil and reclean as needed.
101 TT maintenance.. Enjoy..