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Just note of caution. It is possible the manufacturer is engaging in CYA, but...

PRODUCT OVERVIEW
MSDS/TDS TECHNICAL INFO
ABOUT NEVERWET - HOMEOWNER USE
Rust-Oleum® NeverWet is a two-step product system designed to create a moisture repelling barrier on a variety of surfaces. It is suitable for use on metal, wood, aluminum, galvanized metal, PVC, concrete, masonry, asphalt, vinyl siding, fiberglass, canvas, most plastics and more. Read the NeverWet instructions for more information about application and use.
Not intended to be applied to electronic devices or clothing
Sprays clear and dries to a flat light haze
Durable formulation, ideal for indoor/outdoor conditions
Dries fast — 30 minutes to touch
FOR BEST RESULTS
NeverWet Top Coat should be reapplied when water no longer rolls off of the surface.
AVAILABLE SIZES
Kit
Kit Components
 
I wonder if they're just saying not to put it on phones so that they're not liable for it. As long as the spray itself doesn't mess it up it may just be an extra layer of protection.
 
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