From my notes given to me by Indiana General years ago they say that several types of protective coating and coverings are available for many magnets. Due to the porosity and high resistivity, Ceramic magnets cannot be electroplated. Most Alnico magnets can be plated to prevent corrosion and a covering suitable for soldering. Cast alnico magnets can be electroplated with cadmium, copper, nickel, zinc, tin, and gold plating. Many of the “Alnico” P-90 shaped pickups with rectangular alnico 5 pole pieces are gold and nickel plated according to designer Seth E. Lover. The plating helped when soldering the elevator legs onto the bar magnet for pole height adjustment. When the alnico magnets are cast it’s harder to plate due to poor adherence and imperfections that occur. The porosity of sintered alnico magnets makes it difficult to plate successfully. If the magnets are impregnated with a suitable material or light machining, better plating will result.

Many magnets are often painted with silver paint, especially permanent magnets in analog meters. Flux output is usually unaffected by insulations.