UV protection comes from the tightness of the weave. There is no physical way a coating on the outside of woven cloth could stop light from passing through the voids in the fabric.Please remember that the UVF/SPV are coatings on fibers and do wear off after a certain number of washes (the manufacturers should be stating this), please don't use these as your only defense against the sun.
UV protection comes from the tightness of the weave. There is no physical way a coating on the outside of woven cloth could stop light from passing through the voids in the fabric.