Parylene is a transparent plastic "second skin" for magnets, and it is made in a way that sounds like magic: the coating is grown from a gas, inside a vacuum chamber. Solid parylene is heated until it turns to vapour, the vapour is broken into reactive molecules, and those molecules land on the magnet and link together — molecule by molecule — into an ultra-thin, crystal-clear polymer film. Hold a coated magnet and you usually cannot tell it is coated at all.
Why a gas beats a liquid
Because the coating arrives as a gas, it goes everywhere: inside tiny holes, around corners, over the sharpest rims. Liquid coatings drain, pool and miss surfaces; a gas misses nothing. That makes Parylene the champion for small ring and tube magnets, where plating and paint simply cannot reach the inside.
What it protects against
The film is waterproof, damp-proof and resists acids, alkalis and solvents — Parylene-coated magnets have survived over ten days in hydrochloric acid. It is also an electrical insulator, so one ultra-thin layer gives both corrosion protection and insulation in a single step, helping small parts meet IP dust and water ratings.
When to choose it
The process runs at room temperature, so the magnet never gets hot and its magnetic strength is untouched. The trade-off is cost: per part, Parylene is pricier than plating, so it earns its keep where geometry or insulation demands it — tiny rings for motors, sensors, actuators and the electronics inside phones and wearables.
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