Not That I Am Into Gory Movies,

but every so often I watch a scene,

where a knife cuts into some one and the wound appears to bled, not that I am saying this is how it is done, but the video above gives a very good stab at explaining the effect, using a combination of ferrochloride and potassium thiocyanite which makes the blood, then 'magic' water, sodium fluoride makes it all turn transparent again, as the presenter says watch it as soon as you can incase YouTube takes the video off, it has to be said what a neat blood trick, the clip is from The Action Labs, where there are so many neat tricks.