Own saliva gets out own blood??

[granola shoes]

"Science" was my best guess for this, so please move if needed.

Yesterday, one of my coworkers - one of the well-educated ones - came into my cubicle, and this came up in discussion somehow. Apparently, she learned (from some teenagers, no less) at a BBQ that one's own saliva will get out one's own blood - something to do with the enzymes in it. So if you have a little of your own blood on your clothing, supposedly your own saliva will break it down and remove the stain.

I'm absolutely skeptical of this - anyone heard of this before? I searched here and on the main page but didn't find anything related.

[candy from strangers]

I hadn't heard this, but I cut myself when I wasn't near water and my spit didn't get the bloodstain off my jacket. Of course there was a fair bit more blood than spit, so that could be a factor.

[BluesScale]

Seems unlikely. The main enzyme in Saliva is amylase. That is part of the process for breaking starch (via a long chain of other agents) to glucose. Dried blood isn't starch. Saliva also contains lipase which starts the process of breaking down fats but I can't see that helping all that much.

Blues

[Cervus]

The usual remedy for removing blood from clothing is to immediately wash it in cold water before applying an appropriate detergent. Since saliva is often the only "water" we have available to us all the time, someone may have made the (false) connection that rubbing spit on a stain always has the same effect as rubbing cold water on it. If the bloodstain is small enough and fresh enough, saliva mightremove the majority of the stain, though the item will probably need real H2O and detergent in order to fully remove it. However, saliva won't magically make large bloodstains (or dried ones) disappear.

[BluesScale]

Also, saliva contains a great many cells in suspension so it makes the DNA trace better rather than worse. The Kastle-Meyer Colour Test will still be positive. Potato juice will give a false positive so could be used to cover up residual stains not visible to the eye.

Not that anyone here would want that, of course

Blues

[Troberg]

Well, being a prolific nose bleeder, borderline nose blood fountain, I frequently have a need to get blood stains out of stuff (It's completely unrelated to the night time digging in the garden, I promise!). In my experience, saliva is more efficient than water. Water usually mostly spreads the stuff around, while saliva actually helps getting rid of it.

I have no idea if it's coupled to the person, or if any saliva will do. I strongly suspect the latter.

[Tootsie Plunkette]

When sewing, if you prick your finger and get a spot of blood on white or light-colored fabric, thread a needle with a short length of thread (no knot), put the thread in your mouth and get it soaked with saliva, then run the needle and thread through the blood spot several times. The blood will come out; I've done it more times than I wish to admit.

As to whether this works with someone else's saliva, I don't know. The trick is to do it right away before the blood sets in, so obviously if it's your blood, it just makes sense to use your own saliva (you're right there!). However I have always heard it said that your own saliva will remove your own blood the best.

[snapdragonfly]

I don't have enough spit to really find out.

Best thing is to rinse with cold water to get most of it out, wring out and then use hydrogen peroxide. Hydrogen peroxide works better than ANYTHING I have ever tried. If it's not a huge amount of blood I just use the hydrogen peroxide without cold water first.

It has even gotten out blood stains on clothes that I put through the washer and dryer and came out with some stains still.