You used Baking Soda.
One of the ones below used DE earth and Grapeseed oil.
It looks like we need some type of oil to carry this stuff to the mites.
Read through the forums below for their exact procedure.
Borax and some type of oil carrier would probable get the job done also.
Washing Soda is a natural remedy for a lot of stuff.
Finding that perfect oil to penetrate.
mix 2/3 grapeseed oil with 1/3 Food Grade Diatomaceous Earth (DE) into a spray bottle. Apply to the skin morning & night. Sprinkle DE into the bedding each day with a salt shaker being careful not to breath it. All scabies & itching will be gone within 1 week. Continue treatments for 6 weeks to kill off the hatchlings. DE kills them on contact & the Grapeseed Oil smothers their breathing tube.