
UPF (Ultraviolet Protection Factor) value, also known as the Ultraviolet Protection Factor, indicates the ability of fabric to block ultraviolet rays. It is the ratio of the average effect of ultraviolet radiation calculated without skin protection to the average effect calculated with fabric protection.
UVA transmittance refers to the transmittance rate. It is the ratio of transmitted radiant flux to incident radiant flux within the wavelength range of 315–400 nm, denoted as T(UVA)AV. The T(UVA)AV value is related to the tightness and porosity of the fabric.
In summary, the higher the average UPF value and the lower the UVA transmittance, the better the UV protection provided by the fabric.
Actual testing of UV-protective products: reasons for increases or decreases in values before and after washing:
The case where UV protection is better before washing than after is because certain UV-protective fabrics that have undergone anti-UV finishing or coating maysustain wear or have auxiliary agents come off during wearing or washing, resulting in a decrease in UV protection test values after washing.
The case where UV protection is better after washing than before is due to fabric shrinkage. After washing, the fabric contracts and becomes tighter, thus increasing the UV protection test value of the product post-wash.
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