Solar eclipses are among the most captivating astronomical phenomena that nature offers us. Yet the anticipation of watching the moon hide the sun often leads the general public to underestimate a critical danger: severe and irreversible damage to the human retina. For years, various methods to observe this event have gained popularity, but the moment has come to critically analyze the tools we actually use to protect our vision.
We questioned sector experts and opticians ahead of next Wednesday the 12th, and the answer was unanimous: you should not look at the eclipse with running sunglasses, but you also should not use the so-called certified ones.
The fundamental and unwavering rule of daytime astronomical observation is that you must never look directly at the sun without protection. Conventional sunglasses, regardless of their polarization level or how dark they seem, are completely useless against the direct infrared and ultraviolet radiation of the sun.
The Hidden Problem of “Certified” Glasses
Whenever a visible eclipse approaches, the market floods with the well-known “eclipse glasses” (ISO 12312-2), usually sold under the promise of being properly certified and approved. Nevertheless, we must pause to examine what they are really made of.
In the vast majority, these visors consist of an extremely flimsy cardboard frame that holds a thin piece of plastic film. This material, in many cases, barely differs physically from the consistency of an X-ray.
For a euro and a half you can’t have glasses that protect from anything
The risk of these glasses lies in their extreme vulnerability. Being a simple plastic film, they are susceptible to micro-scratches, imperceptible folds, or microscopic perforations with the slightest touch. A single invisible scratch is enough to allow a beam of sunlight concentrated directly onto the retina. Furthermore, the proliferation of counterfeit glasses with certification seals printed without any real quality control adds an unacceptable risk.
Similarly, the old myth of using stacked multiple X‑rays, CDs, or coated photographic films represents one of the most dangerous practices imaginable. These materials do not function as proper solar filters; they allow radiation to penetrate and burn the macula of the eye. Since the retina lacks pain receptors, the damage (known as solar retinopathy) occurs silently, and its devastating effects are felt hours after the event.
The Safe Alternative: Welding Glasses
If you wish to look directly at the sun during the partial phases of an eclipse while discarding the risk posed by the provided visors, the only truly reliable and unalterable tool is professional welding goggles or face shields.
Unlike fragile commercial visors, welding lenses are built with thick polycarbonate lenses, sturdy and high-density, designed specifically to protect the eyes from intense arc flashes, blinding glints and the very high radiation generated when melting heavy metals. It is not a mere tinted film, but a lens with substantial all-around protection and an unalterable texture.
DIN 14 Filter
For direct and safe solar viewing, you require a welding lens with a shade index of number 14 (DIN 14). Any rating lower than this (such as 10 or 12, common in light welding) will be insufficient and could cause irreparable damage.