The frame makes no difference: what protects you is the filter, which has to meet the EN ISO 12312-2 standard and carry the CE marking. Cardboard, plastic or a handheld viewer are three ways of holding the same filter in front of your eyes, so you choose for comfort. And comfort counts, because on Monday 2 August 2027 you’ll be putting them on now and then for more than two hours: in Madrid, the partial phase runs from 09:45:35 to 12:02:42, and only inside the path of totality are there a few seconds without a filter, around the maximum, which comes between 10:46 and 10:51. All times are Spanish time (CEST, UTC+2).
Three ways of holding the same filter
The Trío de Eclipses website, from Spain’s Ministry of Science, makes no distinction between materials: glasses can come “with a frame (like ordinary glasses) or as a sheet in a cardboard mount”, and either way they have to hold the filter firmly so that it doesn’t come loose, cover both eyes at once and have no sharp edges or irritating materials. The American Astronomical Society (AAS) adds the third form, the handheld viewer, which you hold in front of your eyes.
| Cardboard | Plastic | Handheld viewer | |
|---|---|---|---|
| What it is | A sheet of filter in a cardboard mount | A rigid frame, like that of a pair of glasses | A piece with the filter that you hold in your hand |
| What the AAS says | Keep it dry: if it gets wet, it swells and will most likely come away from the filters | Makers of rigid plastic ones often include a microfibre pouch for cleaning the lenses | Hold it in front of your eyes, or in front of your prescription glasses if you wear them |
Cardboard is the format of the big giveaways: the two million free glasses that the Spanish government and ONCE (Spain’s national organisation of blind people) announced last summer came “on cardboard”. A handheld viewer keeps one hand busy; in return, it doesn’t rest on your face.
No frame fixes a bad filter
EN ISO 12312-2 is the standard for filters for looking at the Sun, and the glasses recalled in Spain last summer failed precisely there: according to OCU, Spain’s consumer organisation, the filter’s transmittance was “below the established minimum” and it was so dark that you couldn’t see the Sun. We tell the story in fake and recalled eclipse glasses.
A damaged filter can’t be fixed either. The AAS says to throw the glasses away if the filter is torn, scratched or punctured, or if it is coming away from its frame, whether that frame is cardboard or plastic. The Trío website adds creases, lighter patches and any other defect, because “a single weak spot can let through enough light to damage your sight”.
Over prescription glasses
If you wear glasses, don’t take them off. The AAS puts it like this: leave them on and put the eclipse glasses over them, or hold the handheld viewer in front. Here the shape does matter, so try it before the day: the eclipse glasses should fit over yours without slipping or, if they don’t, the viewer should feel comfortable. The details are in eclipse glasses with prescription glasses, contact lenses and cataracts.
With children
On a child, the filter has to cover both eyes without moving. The AAS asks adults to supervise children using solar filters at all times, and if the child also wears prescription glasses, the Trío website recommends “supervision and even holding by an adult”. We haven’t found any official source that talks about sizes: try them on the child beforehand and stay by their side. More ideas in eclipse glasses for children and in watching the eclipse with children (in Spanish).
How to store each one
Each frame is looked after in its own way: cardboard, dry and flat; plastic ones, in their case, which according to the AAS usually comes as a microfibre pouch for cleaning the lenses. Everything else is in do eclipse glasses expire? (in Spanish).
Ours
Whatever the frame, the filter is always checked the same way, and that is what our guide to certified glasses is for.
On Order your glasses you can ask for ours: cardboard, with the EN ISO 12312-2 certificate, along with the phone filter and packs for groups. We reply with the price and the delivery time.
Sources: Trío de Eclipses, Ministry of Science — Salud visual (in Spanish: a frame or a sheet in a cardboard mount; hold the filter firmly, cover both eyes and no sharp edges; when not to use them; a single weak spot; children with prescription glasses); AAS — How to View a Solar Eclipse Safely (eclipse glasses and handheld viewers; cardboard, dry; the microfibre pouch of rigid plastic ones; over prescription glasses, or the viewer in front; supervise children); AAS — How to tell if viewers are safe (throw away a filter that is torn, scratched, punctured or coming away from the frame); AAS — Suppliers of Safe Solar Viewers & Filters (ISO 12312-2, the standard for filters for looking directly at the Sun); OCU — recall of eclipse glasses (in Spanish: the recalled glasses failed in the filter); Trío de Eclipses — the government and ONCE giveaway and ONCE — the free glasses giveaway (in Spanish: two million, on cardboard); times for Madrid and for totality: eclipseando data (skyfield engine + DE440s).
If you would like something to keep from the eclipse, the shop prints T-shirts, mugs and posters with the name of your town, the time of its maximum and its seconds of totality. See the merchandise →
Remember: never look at the Sun without proper eye protection (filters made to EN ISO 12312-2). The official reference for safe viewing in Spain is the IGN (in Spanish): eclipses.ign.es.