Hi Ken
My wife is a collector of plates and plates and plates and plates she is now into Elvis plates , that hang all over the walls LOL
, I have made many racks for them out of 3/8" and 1/2" Walnut because it's strong and stable for it's size and with a clear coat wipe on poly. it's beautiful wood with a clear coat on it. 
Bj
My wife is a collector of plates and plates and plates and plates she is now into Elvis plates , that hang all over the walls LOL
Bj