With just hours to go until the August 2026 solar eclipse, many would-be observers have found themselves unable to get a pair of solar eclipse glasses in time.
Which begs the question – can't you just use those old solar eclipse glasses that have been hidden away in a box in a wardrobe for the past few years?
Ultimately, solar eclipse glasses are the only safe way – other than solar filters and solar telescopes – to be completely safe when observing a solar eclipse.
They block out 99.99% of the Sun's harmful rays and heat, leaving you with a clear, safe view of the solar eclipse.
Even if the Sun is 99% obscured by the Moon, that's still a partial solar eclipse and solar eclipse glasses must be worn.
And you must wear solar eclipse glasses that conform to the ISO 12312-2 safety standard, as this means they adhere to strict safety rules and they've been made by a responsible, competent manufacturer.
But what about an old pair? Technically, if they were bought within the last three years or so, they should be fine, but you'll need to examine them very, very carefully for bends, tears, scratches and pinholes.
Any amount of sunlight getting through a pair of eclipse glasses means they don't work. If in doubt, don't risk your eyesight.
Hold them up to a light bulb. Can you see any tiny pinpricks of light, or places where light is clearly passing through? That likely means they're damaged and you should discard them.
The American Astronomical Society are experts on the subject and they say that, if your eclipse glasses or viewers are 10 years old or older, you should not use them.
That's because materials, manufacturing methods and safety standards have changed somewhat in the past 10 years, but also because 10 years is too long to be fully confident the solar eclipse glasses are still working as they should be.
The full statement from the American Astronomical Society says: "If your eclipse glasses or viewers are less than 10 years old; if their manufacturer has had them tested by a properly accredited laboratory that has found them to conform to the ISO 12312-2 standard; and if their solar filters aren't scratched, punctured, torn, coming loose from the frame, or otherwise damaged, you may reuse them."
Find out more in our guide on how to make sure your solar eclipse glasses are safe.
If in doubt about your solar eclipse glasses, our advice would be not to risk it, given the potential dangers of observing a solar eclipse without wearing ISO 12312-2 solar eclipse glasses in good condition.
Instead, you could try projecting the solar eclipse through a piece of card or a colander, and indirectly observing the eclipse by watching the shadow of the Moon cast onto another piece of card.
You can find out more about that in our guide on how to see a solar eclipse without solar eclipse glasses.
