what are solar eclipse glasses made of

Solar eclipse glasses are made of a black polymer or silvery mylar that blocks 100% of infrared and ultraviolet light. They only transmit about one millionth of the suns visible light. The lenses are about 100,000 times darker than ordinary sunglasses and block nearly all visible light as well as all infrared and ultraviolet light. The black polymer is a flexible resin infused with carbon particles. The main filter thickness of the glasses consists of an oriented polymer that has been darkened with carbon black. Solar eclipse glasses have their safety certified by the International Organization for Standardization (ISO) and must meet the ISO 12312-2 safety specifications. The recommended optical density of this eyewear is 5. Regular sunglasses or homemade solar filters are not safe for watching an eclipse because they transmit sunlight at a rate that is thousands of times too high.