Blood From A Stone

October 1, 2009 4:41 PM

Blood. Let's say...a bucket full of blood. Now pour that on a flat stone surface. Then put that under the hot sun. Go away. But come back in a week or two. What's left? Anything?

Put aside wind conditions and all that. I just want to know how the heat affects the blood and whether or not you could determine if there was blood there at all after a few weeks time.

I could assume but we all know how that usually works out.

Asking for fictional purposes.

Thanks!

posted by ryecatcher to science & nature (7 comments total)

I think it depends enormously on whether there is a big ant's nest in the area. If so, there may well be little left of the blood clot that would form, because the ants would scavenge it.

But even in that case there would still be recognizable black/brown residue in the cracks of the stone surface. And it would definitely be detectable by scientific test.
posted by Chocolate Pickle at 4:47 PM on October 1

I can attest from days spent squishing enormous blood-filled woodticks (plucked from our poor dogs) that the stains do stick around for a while, but they eventually wash away.
posted by GaelFC at 4:53 PM on October 1

Not a bucket full of blood, but a pothole full of blood at the end of my driveway. Even after being washed out/decontaminated by EMS guys while the blood was fresh, after 1 1/2 weeks in the baking Austin sun (and no rain at all) there were still dark splotchy stains visible. Also, it smelled extremely interesting to the dog the first time she was there post-accident (4-5 days), who ran directly for the spot and sniffed around for several minutes. After a week or so we used some bleach water on it and the spots became less noticeable, but still visible if you know where to look. It would undoubtedly be recognizable as blood with Luminol or other scientific tests.
posted by katemonster at 5:13 PM on October 1

(For reference, the bleeder was on Plavix and aspirin, so the blood did not clot quickly. Circumstances might vary for someone with normal clotting.)
posted by katemonster at 5:15 PM on October 1

Detection after a week or two? No problem. Luminol can measure nanograms of blood left behind several years after the event. If there are any slight cracks or irregularities in the surface for the blood to seep into and hide in then it's even more likely. Degradation of the blood isn't a problem since luminol is activated by the heme components of the blood rather than intact blood cells.

Here's a good review. Setion 3.1 is proably the most relevant for your question.
posted by shelleycat at 5:26 PM on October 1

I've been searching to try and find the effects of heat on bloodstains to see what would physically happen to it as well but keep getting results referring to effects of heat on DNA within the blood. Based on general biology the blood will dry into a film on the stone, possibly lumpy since you're talking about quite a lot of blood. The heat will cook the blood denaturing the proteins and making it turn brown. It will also speed up bacterial degradation of the blood (stinky) which will eventually make it all go away. But if there are no environmental conditions to worry about, it's not scraped off at all, and there are no bugs it could take a really long time to fully degrade and disappear. I've seen blood stains last for many months, although they were on a porous surface. After a week I'd expect there to be visually noticeable stains left behind, but I don't know if you're still talking a film of obvious blood or just brown bits in the cracks by then.

There's a lot of discussion of bloodstain evidence in forensic journals and books and presumably there's a definitive answer in there somewhere. Apparently I'm too stuck in molecular biology mode today to find it.
posted by shelleycat at 6:02 PM on October 1

I once dumped about two gallons of blood, at the start of summer, on soil without a great deal of grass. In a couple of weeks, nothing would draw your attention. No rain was present to wash it away, other than a light shower one day. I'm sure someone who was looking for it, with the right stuff, could find it, but nothing obvious was evident either to my eyes or to my nose, and I looked pretty close. The soil looked a bit darker in that spot, but it was not outside the normal variation.
posted by adipocere at 6:56 PM on October 1