Ferrite, Samarium Cobalt and AlNiCo magnets are usually uncoated because they do not rust/oxidise. Neodymium magnets are available uncoated but this is not common.
Ferrite, Samarium Cobalt and AlNiCo magnets are usually uncoated because they do not rust/oxidise. Neodymium magnets are available uncoated but this is not common.