Concerns have been raised about powder and spray sunscreens damaging lungs, and the FDA is still evaluating the toxicity risks of these products.

FORBES: FDA Delays Implementation Of New Sunscreen Regulations Until After Summer

General Motors has discussed Branagan's spray-on powder for auto bodies and parts as a substitute for heavier coatings.

FORBES: Magazine Article

The spray-on metal powder is 50% to 70% iron.

FORBES: Magazine Article

But if you heat up the alloy until it liquefies--Branagan's powder must be heated to 1, 200 degrees Celsius and applied with a thermal spray gun--it turns into an ashy powder as it cools, a metallic glass with "frustrated" molecules, as Branagan calls them, anxious to form a lattice, but confined by their inability to move.

FORBES: Magazine Article