One, look at the label. It mainly depends on the protection index, namely the UPF and UVA values. Only when the UPF is greater than 40 and the UVA transmittance is less than 5%, can it be called an anti-ultraviolet product. The higher the UPF value, the better the UV resistance. Generally speaking, most of the trademarks on the market are "UPF50+", and its protection function is sufficient.

　　Second, look at the color. In the case of the same fabric, dark umbrellas have better UV protection. The biggest difference between hanging umbrellas and other umbrellas is that they have an anti-ultraviolet coating to prevent the penetration of ultraviolet rays. The ultraviolet transmittance of black fabric is 5%, the ultraviolet transmittance of navy, red, dark green, and purple fabrics are 5%-10%, and the ultraviolet transmittance of green, light red, light green, and white fabrics is 15%.

　　Third, look at the fabric. The thicker the umbrella surface, the tighter the fabric and the better the UV resistance. Compared with cotton, silk, nylon, and other fabrics, polyester is more sun-proof. If you want to know the sun protection effect of a hanging umbrella, you can try it in the sun. The darker the shadow, the lower the light transmittance, and the better the sunscreen effect.

　　1. Silver-plated fabric. The silver belt fabric not only has a good anti-ultraviolet effect but also the price is relatively cheap. When using, pay attention to the silver glue coating not to get wet. Rain will damage the umbrella coating and reduce the sun protection effect. If the umbrella is used for a long time, the silver glue coating will age and turn black. Sometimes you will find that the coating will appear one after another. This is because the weather is dry and the coating shrinks. To ensure the sun protection effect, you need to replace the umbrella.

　　2. Two new fabrics. TC fabric is a new type of fabric, which can be washed without affecting the sun protection effect. The light transmittance is not high, and it can block ultraviolet rays with wavelengths of 380,300 and 220nm respectively. Ultraviolet rays in the 250-400nm band can easily cause sunburn and dryness of the skin and hair. There is also a laser-punched fabric that is woven with high-density technology. There are many refracting particles on the surface of the fabric, and each small point will change color with the rotation of the light position, playing the role of scattering ultraviolet light. These two kinds of fabrics have better UV resistance, but they are more expensive.

　　Three, three kinds of fashionable fabrics. The fat and thin silk look like lace, which is super light and beautiful. However, the light transmittance of this fabric is high and the sun protection effect is not good. The dyed fabric is a kind of satin fabric, belonging to polyester fiber. Its anti-ultraviolet effect is weaker than silver-plated fabric. There is also a kind of fabric called pearl band on the market, which has a certain reflection effect on ultraviolet rays, and its sun protection effect is worse than silver-plated fabric.