Therefore, anti-reflective coatings with more scratch-resistance are preferred in art glazing. Magnetron-sputtered and sol-gel anti-reflective coatings are typically metal oxides with superior hardness compared to other application methods. UV Filtering Coatings In order to reduce the amount of damaging light radiation transmitted through glazing, some glass coatings are designed to either reflect or absorb the ultraviolet (UV) spectrum. The following technologies are used to reduce the amount of UV from reaching the artwork: Organic UV Absorbers are added to an inert, inorganic silica-based coating to yield a UV absorbing layer on one side of the glass. Organic UV absorbers are capable of blocking almost 100% of UV radiation between 300 nm to 380 nm, but in an industrial environment it is difficult to make a sharp UV cut-off without affecting the visible spectrum, therefore UV absorbers tend to also increase the absorption of the visible light. Chemically-deposited UV absorbers also result in a less scratch resistant surface than magnetron-sputtered or Sol-gel UV blocking layers, as evidenced by the manufacturer's recommendation for avoiding environmental and other contact with the UV-coated side. Interference UV Blockers are usually built into anti-reflective interference thin film stacks, and focus on maximizing the UV reflection below the visible light boundary. Industrially-available sol-gel processes offer up to 84% UV block, while magnetron-sputtered AR/UV-Blocking layers can block up to 92% with no adverse effects on the transmission or absorption of visible light. UV Filtering of the Substrate is possible by adding UV filtering agents during the production of the substrate. While typical clear float glass blocks approximately 45% of UV radiation, the addition of CeOx to glass has been shown to further reduce UV transmission as well as widespread use of organic UV blocking dyes in the production of acrylic substrates. Most soda-lime glass completely absorbs short wavelength UV-B radiation below 300 nm. Low-iron glass typically blocks approximately 12% of UV radiation between 300 and 380 nm. UV Protection in Art Glazing UV Definition in Art Framing The most widely used definition of "UV Light" in the framing industry has been defined as non-weighted average transmittance between 300 nm and 380 nm, while the ISO-DIS-21348 standard for determining irradiances defines various UV light ranges: The definition of the upper limit of UV protection as 380 nm by the framing industry is not consistent with accepted standards above. According to the Library of Congress Preservation department, the artwork damage