The effects of open porosity and constructional parameters on cotton woven fabric's ultraviolet protection factor

The paper presents the results of research dealing with the effect of fabric construction on the ultraviolet protection factor (UPF) of light coloured cotton woven fabrics. The type of weave, absolute fabric density, and relative fabric density were taken into account to define the effect of fabric construction on UPF. To establish quantitative relationship between the fabric construction and UPF, the open porosity was used as a parameter which defines the woven fabric constructional parameter's combinations. Fabrics in a raw state (loomstate, light brown fabrics), along with bleached and calendared fabrics (white fabrics) made from 100% cotton staple-fibre yarns were used in this research. Loomstate fabrics were constructed with different types of weaves (plain, 2 x 2 twill, 1 x 4 satin), at threedifferent levels of relative fabric density (around 60%, 70% and 80%), while bleached fabrics were constructed in plain, 2 x 2 twill, and 2 x 2 mattweave, with the same warp density and different weft density at four different levels (15, 19, 23, and 29 picks/cm). The results clearly indicate that lower open porosity leads to better ultraviolet protection. The effect of weave is evident only when samples are comparable in fabric relative density. Higher absolute fabric density also means superior UV protection. Moreover, the results also indicate the values of open porosity and fabric densities by which the fabric achievesgood UV protection (UPF=15) - and in this way, they can serve as guidelines for fabric engineers when developing a new type of fabric construction that encompasses sufficient UV protection ability.