Measuring UV – Testing the Shade of Different Hats and Parasols
We’ve all been told that wearing a hat or sitting under a parasol will help protect us from the sun’s harmful rays. But how much protection do they actually give — and does it vary by material, colour, or style?
Armed with a @pascoscientific wireless Light sensor, I decided to find out. This Light sensor can detect and measure the UV Index as well as the amounts of UVA and UVB reaching it.
Why Measure UV?
Sunlight contains ultraviolet radiation, which can cause sunburn, premature skin ageing, and increase the risk of skin cancer. While sunscreen is an obvious defence, many people rely on hats, sunglasses, or parasols for extra shade. Measuring the UV passing through these barriers tells us just how effective they really are.
The Experiment
Equipment:
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PASCO Wireless Light Sensor
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A selection of hats: straw sun hat, cotton baseball cap, wide-brimmed synthetic hat
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A collection of parasols: light fabric, dark fabric, reflective silver coating
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A sunny summer afternoon (the most difficult thing to arrange in the UK!)
Method:
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Place the UV sensor in full sun to record a baseline reading.
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Position the sensor under each hat or parasol in turn.
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Record the UV reading for 30 seconds to average out any small fluctuations.
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Compare the results as a percentage of the baseline.
What We Found
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Straw sun hat – Let through surprisingly high amounts of UV due to the gaps in the weave. Stylish, but not much help on its own.
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Cotton baseball cap – Good protection for the top of the head, but leaves the face, ears, and neck exposed.
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Wide-brimmed synthetic hat – Excellent coverage and low UV penetration, especially when the fabric had a dark colour.
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Light fabric parasol – Reduced UV but still let through a fair amount, especially when the sun was high overhead.
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Dark fabric parasol – Significantly better than the light fabric, with lower UV readings underneath.
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Silver-coated parasol – The clear winner, blocking almost all UV in the measured range.
Key Takeaways
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Fabric density matters – tightly woven materials block more UV.
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Colour counts – darker colours tend to absorb more UV than lighter ones.
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Coverage is crucial – a hat might protect your scalp, but without a brim or neck flap, other areas are still at risk.
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Reflective coatings work – parasols with a metallic or silver underside can dramatically reduce UV exposure.
Why This Matters for Everyday Life
If you’re spending long hours outside, whether gardening, sailing, or enjoying a café terrace, it’s worth knowing how effective your shade really is. Your hat may keep you cool, but it might not be keeping you safe.
With the right choice of material and design, hats and parasols can become powerful allies in UV protection — and our measurements prove it.
🎓 Science Outdoors, Made Easy
At Philip M Russell Ltd, we believe science happens everywhere — not just in a lab. With wireless sensors, simple experiments, and a curious mindset, we help students explore physics in the real world.
Whether it’s tracking sunlight in the garden or building graphs from everyday items, we teach GCSE and A-Level Physics through discovery and data.
📅 Now enrolling for 1:1 Physics Tuition – online and in-person, in the Lab
With experiments, real data, and clear explanations.
🔗 www.philipmrussell.co.uk
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