By The Numbers Quickie: White and Black Garments Solar Gain Comparison

Which color is best for UV resistance?

I’d always thought that dark or brightly pigmented clothing provided more UV protection, but this review article suggests that it’s a bit more complicated than that (there’s a “regular clothing” section if you scroll a bit). Apparently quantity/intensity of dye also plays a role…?

Hi Terran: In principle, dark colors will have lower UV transmission. These were pretty thick cotton, so who knows? I have used UV Intensity Cards from Amazon that allow cheap,useful and simple comparisons of clothing performance. If the sun comes out today, I can see if I can measure anything through these shirts with a card.

Thanks Stephen.

Thinking that thickness and weave would effect UV exposure as well as color. With a thin breathable fabric for a sun shirt, color is more critical. There becomes a compromise between UV exposure and accumulated heat.

Terran: Those things are all true.  Further, for sunburn, you don’t want to measure just UVA or UVB.  The measurements must be taken using the Diffey erythemal action spectrum. This weights spectral components by their probability of producing sunburn. So, the cards have limited use. I may purchase an instrument that can do this, as it is a subject in which I have some interest. Stay tuned.

Down another rabbit hole? Way cool. I think it would be very helpful information. Another variable might be how a fabric preforms when soaked in sweat. Very much appreciated.

What I hope to measure is the fractional reduction of UVA and UVB according to the erythemal action spectrum. This spectrum is weighted to the wavelengths most likely to result in skin damage. I hope to figure our how the warnings about color type, fabric thickness, etc. impact likely skin damage. We shall see.  So yeah, another rabbit hole.

What role does distance play? I believe light will defuse when passing through fabric, the light waves will weaken. A bellows style shirt seems to work well in this regard. The light energy either bounces off, is absorbed, or is confused as it passes through. As the distance from the fabric grows like in a tent, does the light energy reconstitute?

Hi Terran: Let’s not get ahead of ourselves. The new instrument will arrive on Monday and then I will go about adapting it to my envisioned task. Then, I will start testing fabrics and see if what I want to do seems feasible.  After that, let the discussion begin.

Chasing rabbits…looking forward to your observations.

I bough a UV card from Amazon to measure a newly purchased OR Echo’s UV blocking ability compared to an older-2-3 year old heavily used but in good repair Echo. The problem with the UV card is they react very vast and trying to capture the cards measurement as soon as the shirt is removed is difficult.  I would love to see someone with real equipment test this.