​Do Eclipse Glasses & Handheld Viewers Expire?
If your eclipse glasses or viewers are compliant with the transmittance requirements of the ISO 12312-2 safety standard, and if their filters aren't scratched, punctured, torn, coming loose from the frame, or otherwise damaged, you may reuse them indefinitely. Furthermore, you may look at the uneclipsed or partially eclipsed Sun through them for as long as you wish. Some glasses/viewers are printed with warnings stating that you shouldn't look through them for more than 3 minutes at a time and that you should discard them if they are more than 3 years old. Such warnings are outdated and do not apply to eclipse viewers compliant with the ISO 12312-2 standard and in excellent condition. And to maintain your solar viewers in excellent condition, store them at room temperature, either in the case or package they came in or in an envelope or other container that will keep them clean and dry and protect them against scratches and punctures.


Is It Safe to Clean Eclipse Glasses and Handheld Solar Viewers?
Manufacturers of hard plastic eclipse glasses often supply a microfiber pouch that you may use to wipe the lenses clean. The same pouch may be used on the lenses of cardboard eclipse glasses and handheld solar viewers. You may also wipe them clean with any soft, nonabrasive tissue or cloth; Kimwipes are also suitable, but baby wipes and other wet wipes are not suitable. Cardboard must be kept dry; if it gets wet, it will swell and likely detach from the lenses. Do not use water, glass cleaner, or any other solvents or liquids to clean cardboard eclipse glasses and handheld solar viewers.
Are Welding Filters Safe for Solar Viewing?
The ISO 12312-2 standard was based, in part, on decades of experience using welding filters for observing the Sun. A welding filter with a shade number of 12 or higher transmits a safely tiny percentage of the Sun's light across the spectrum, whether made of tempered glass or metal-coated polycarbonate. Most observers find the view through a shade 12 welding filter uncomfortably bright and the view through a shade 15 or higher-numbered welding filter unattractively dark. The "sweet spot" is shade 13 or 14, which best matches the view in purpose-made eclipse glasses and handheld solar viewers, except that the image is green rather than yellow-orange or white. Shade 13 and 14 welding filters are rarely stocked in welders' supply stores, though, so you'll probably have better luck finding them by shopping online. A good source of glass shade 14 welding filters is safesolarviewing.com.

You should not use adjustable and/or auto-darkening welding helmets or similar products to view the Sun. Many don't go as dark as shade 13 or 14, and even those that do post a grave risk to your eyesight, either because you accidentally adjust them to an unsafe setting or because they don't auto-darken fast enough when you look at the Sun with them.

A solar eclipse is one of nature’s grandest spectacles. By following these simple rules, you can safely enjoy the view and be rewarded with memories to last a lifetime.

This safety information is provided by the American Astronomical Society (AAS), the National Science Foundation (NSF), the National Oceanic and Atmospheric Administration (NOAA), and the National Aeronautics and Space Administration (NASA) and the Canadian Space Agency (CSA). It has been endorsed by the Canadian Association of Optometrists, the Canadian Ophthalmological Society, the American Academy of Ophthalmology, the American Academy of Optometry, the American Medical Association, the American Optometric Association, the American Society of Retinal Specialists, and Prevent Blindness.


Note: This web page does not constitute medical advice. Readers with medical questions should contact a qualified eye-care professional.

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