cloth dyed with natural dyes works as sunscreen?

"Clothes dyed with natural dyes protect skin from harmful UV rays"
I want this to be true as this article suggests. I grow and use plant dyes and other natural dyes exclusively and would love to know that when used to dye natural fibers that they could work both as a sunscreen and/or medicinally against the skin.

this is the link....here

has anyone heard of this?

Yes, what is in the article is generally true. But.....to explain more, we need to have a short tutorial on Beer's law.

Beer's law relates to how much radiation will get from source to target when there is some material between the two. The three factors are: distance between the source and the target, concentration of the absorber between the target and the source, and the extinction coefficient of that absorbing material. "Extinction coefficient" is the chemist's way of quantifying how much of the radiation the material can 'extinguish' before it gets from the source to the target.

If you go to the top of a mountain, say 14,000 feet, you will be much more likely to get sunburned. Not because you are almost 3 miles closer to the sun (3/93,000,000 is effectively zero), but because you are above half of the atmosphere that is absorbing the sun's rays.

So we go back down to sea level and we have more air to protect us. But air doesn't screen out much UV. Neither does glass. Plastic does a good job though. Ever see someone who wears plastic sunglasses a lot? Their face may be tanned from the sun's uv, but the they have raccoon eyes where the plastic blocked that uv. In general, organic molecules absorb pretty well in the uv. Colored organic molecules absorb even more. If you were just to paint olive oil on your skin, that would be better than nothing at all. Take some flower petals and extract their color into the olive oil though, and now you have an even more effective sunscreen.

A common ingredient in sunscreens is para-aminobenzoic acid (PABA). Having an aromatic ring, this is going to absorb a lot of the radiation between 200 and 300 nm, which is the region of the spectrum that you are trying to protect yourself from.

Another thing to point out in designing your own sunscreen is that two materials are better than one -- as long as they absorb in different regions of the spectrum. PABA doesn't really have any color, so it is only absorbing in the far uv; if you are extremely sensitive to the sun, you want to get some yellow or orange colored material that absorbs further into the visible region of the spectrum. Or put on two coats of the PABA. That would be the concentration effect -- a 2mm coating of sunscreen is twice as effective as a 1mm coating.

But have at it and experiment. Take chrysanthemum flowers and mix them with bear fat and you've got a recipe for paleo-sunscreen.

Thanks, John...I hadn't thought of just adding the dye to a fat or oil , that would probably be more effective and could be interesting color wise....I was thinking the article was meaning natural dyed cloth and wondered about a scarf or shirt or something. I am very fair skinned and have had many removals from bad sun exposure in the past....so this sounded like something that might help...depending on the color, of course...I would imagine my bodark dye could do some crocking mixed with sweat.