It is essential that you use
cold water when removing
blood stains. This is because at
high temperatures hemoglobin will get
denatured and then it will get stuck onto the
fabric because the denaturing of this particular
protein is
irreversible.
Fresh stains are especially easy to
get rid of - just
soak in
cold water, maybe a tiny bit of regular unscented
soap with an old toothbrush.
For us females, this removal of
blood from fabric is sometimes a
monthly process, so it's especially important to know.