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Sun protection by a summer-weight garment: the effect of washing and wearing
D G Stanford1, K E Georgouras, M T Pailthorpe
1Dermatology Centre, Liverpool Hospital, Sydney, NSW.
Objective:
To assess the effect of use (washing and wearing) on the photoprotection provided by a cotton fabric.
Methods:
Twenty jersey-knit pure cotton T-shirts were worn for 4-8 hours per week and washed weekly for 10 weeks. Fabric samples taken before and after use were compared.
Main Outcome Measures:
Fabric ultraviolet protection factor (UPF) was calculated from spectrophotometric ultraviolet radiation transmission data. Changes in fabric structure and hole size were determined for samples from one T-shirt by light microscopy and image analysis.
Results:
UPF increased consistently and significantly after use, from a mean of 19.0 to 40.6. A corresponding reduction in fabric hole area was seen under the light microscope and confirmed on image analysis (from 8.0% to 3.9% of total image area).
Conclusion:
UPF of pure cotton garments may improve after use, at least in the short term. The increase is mostly accounted for by reduction in fabric hole area due to shrinkage.