A WhatsApp channel which advertises stock in corner shops – including some offering delivery – has attracted thousands of followers in a matter of days.
Elsewhere, hopeful buyers in Reddit and Facebook threads are directed to online marketplaces, including for more expensive bulk purchases.
“Be cautious of products sold online,” advises the UKHSA. “If you’re unsure whether a product is certified, don’t use it.”
UKEclipse, an initiative set up by UK astronomers, also warns that major eclipses often attract “counterfeit and substandard” glasses and advises going through specialist retailers and organisations instead.
The American Astronomical Society (AAS) urges eclipse chasers to check its list of manufacturers which it has confirmed test their glasses properly in a lab.
Those who have managed to find a pair can try them ahead of time, it says, by testing them both inside and outside on a sunny day.
In both settings, you should not be able to see anything other than perhaps very bright lights, including the Sun’s reflection off a shiny surface, “which should appear very faint”.
If they pass that test, you can glance at the Sun – only for less than a second – and should only be able to see “a sharp-edged, round disk… that’s comfortably bright, with a dark background all around it”.
“If your viewers pass all three tests, they are probably safe,” it says.