The reason why umbrellas can block ultraviolet light is because they are made with "materials".
For example, in the umbrella cloth mixed with ceramic particles to reflect ultraviolet light, or coated with vinyl, silver glue to isolate ultraviolet light, or in the umbrella surface dyed ultraviolet absorbent.
Which sun umbrella works better?
Sunumbrella with coating: the first choice of vinyl coating, followed by silver glue, color glue sunscreen effect is the most times.
Generally speaking, good quality vinyl sun umbrella, can absorb most of the ultraviolet radiation from the air, the highest transmittance can reach zero.
Not only that, it can also absorb the ultraviolet light reflected on the ground, so the best sunscreen effect.
Now popular "little black umbrella", many are vinyl coated.
However, the price of vinyl sun umbrella, often the most expensive, if you want to pursue cost-effective, silver plastic umbrella is also good.
In addition, like sunscreens, umbrellas have an SPF rating, usually on a hanging tag.