What is the difference between UPF and SPF?
UPF stands for Ultraviolet Protection Factor. It is measure of the UV protection provided by fabric. A UPF rating is granted to apparel or gear that has been tested and proven to block a certain amount of ultraviolet radiation. UPF is similar to SPF, except that UPF means UV testing was conducted with equipment rather than on people's skin. SPF measures the length and time of protection against sunburn from UVB compared to unprotected skin. SPF rating only applies to lotions applied directly to the skin, not fabrics.
What makes fabric sun protective, or UPF rated?
Tightness of knit or weave: basically the tighter the weave, the higher the UPF. When a fabric is stretched, the tightness of the weave diminishes, resulting in increased UVL (ultra violet light) transmission. If a fabrics’ weave is not as tight as desired resulting in a low UPF rating, the fabric can be treated with a Tinosorb finish to raise the UPF. Thicker fabrics generally have higher UPF ratings than thinner fabrics. When fabric gets wet, its UPF protection can decrease dramatically. Wet cotton can lose up to 50% of its SPF/UPF. This is because water reduces the scattering of UVL, therefore increasing its transmission of harmful ultraviolet rays. Dark colors are more protective than white. In a study of identical fabrics, which were either white or dyed, it was found that white cotton fabrics had an UPF of 12, whereas a similarly constructed black fabric had UPF of 32. In testing polyester, the studies showed that a white polyester was a 16 UPF and black polyester was a 34 UPF*. *UPF ratings in this study do not reflect the ratings of all cottons or polyester fabrics.
How long does UPF last in a garment?
The excellent sun protective properties of our fabrics will last the lifetime of the garment, and do not wash or wear out. Does Sunday Afternoons hats or clothing undergo any treatments or washes to obtain their high UPF ratings? Are they dangerous? And will they wear off over time? We at Sunday Afternoons have very high standards for the UPF ratings of our fabrics. Sometimes if a fabric does not meet a high enough UPF rating, we will treat it with a Tinosorb finish applied during the dying process of the fabric that increases UPF ratings. Tinosorb finishes are safe for skin. The finish permanently bonds with the fabric and will not wear off for the lifetime of the product. If you would like to learn more about Tinosorb click here
Why isn't the mesh UPF rated?
In our lasting effort to keep Sunday Afternoons hats cool and comfortable, we add mesh vents to most models. Most of our mesh venting does not offer sufficient sun protection and therefore is not rated. Mesh venting is always placed in areas of the hat crown where most wearers are likely to have hair. Hair is one of the body’s natural forms of sun protection and the hair under the hat vents is likely to be sufficient in protecting ones head. We also offer two hat styles that feature UPF 40+ sun protective mesh (Charter Hat and Highlander Hat) along with a few hat styles with covered mesh panels (Derma Safe Hat, Convertible Cap, and Eclipse Cap). We recommend these styles for people who have thinning or balding scalps and need top of the crown sun protection.
