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Why Blood Is Such a Tough Carpet Stain (VIDEO)

08/07/2013 08:30 am ET | Updated Oct 07, 2013

Join me for a thought experiment. Let's say you borrowed some money from a guy to finance, oh, I don't know, a documentary: "Adam and Eve... And Steve: The story of the first man and women... and their very tidy buddy who lived next door."

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On the documentary's opening night, no one shows up. Except a confused guy in a raincoat who thinks porno theaters now sell popcorn. Anyway, since you don't have his money, the guy you borrowed from appears in your living room and beats on your knee with a tire iron like he's Tommy Lee doing the drum solo from "Dr. Feelgood."

As your knee cap rolls into the kitchen, you realize there's now an Olympic-sized pool of blood on your floor. And crazily enough, blood splatter on the mirror in the downstairs bathroom. Even though the door was closed. And it's a bathroom downstairs.

So, before you start cleaning up the blood, there's one thing you should do: figure out the science behind what you're dealing with. Oh, and you should get your knee cap out of the dog's mouth. OK, two things.

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The average adult has about 10 pints of blood coursing through his arteries and veins. Blood makes up about 7 percent of your total body weight. And as for the blood itself, 65 percent of it is plasma (yellow) and 35 percent is made up of red blood cells -- whose chief component is hemoglobin... which is rich in iron -- whose color is red.

So, why are blood stains so tough to remove from carpet?

Hemoglobin forms relatively strong bonds with the carpet fibers. It's this ability to bond mightily, coupled with the iron's intense "red" color along with its volume, that make blood such a difficult stain to remove.

The amount of blood on your carpet, from a few drops to well, a lot more, will be the determining factor in what you do next. For a large amount -- think, a pint -- first thing you'll want to do is spray the offending area with a bactericide that will kill any blood-borne pathogens, for example: staphylococcus-like and streptococcal-like microbes.

Conversely, if it's just a few drops of blood, the first thing you'll want to do is blot it up. DO NOT rub too hard, or stand on a cloth you place over the stain because all you're going to do is FORCE the blood into the carpet's fibers or you'll cause the blood to seep through the bottom of the carpet and stain the wood floor below (assuming you have that).

Next, you'll want to choose the right cleaning agent.

A cleaning agent like salt, for example, will draw the blood out of the carpet and trap it in between its own molecules. After scraping up the salt, flush the carpet with water or peroxide. Other cleaning agents will "attack" the blood, break it down and thus make the red iron pigment colorless... while the actual biological material might still remain on the carpet, despite your inability to see it.

To find out specifically which cleaning agent -- peroxide, salt, club soda, tooth paste, vinegar, ammonia or just plain old drinking water -- and which method is the very best at removing blood stains from a carpet, check out: Episode #6 of This vs That.

You're invited to check out the first 2:30 minutes of This vs That's blood vs carpet experiment below.

Jon Hotchkiss is the creator of This vs That, the first independently produced 6-hour investigative series that uses science to explain the world within arm's reach. "Like" us on Facebook, here.