Why is the blood red or brown? Shouldn't it be black?
It is a good question. It is heard often. Skeptics will sometimes claim that the blood cannot be real because old blood is black. Actually, old blood often just turns brown. That all old blood turns black is overstated.
Old blood is not always black. Two factors will keep bloodstains from losing all or most of their red color:
- The blood on the Shroud contains significant amounts of
bilirubin, a bile pigment produced by severe trauma. Bilirubin is
bright red and will cause bloodstains to remain red in color.
- Ancient cloth, after weaving was, was often washed in natural soap such as that derived from the Soapwort plant. Ingredients of this natural soap are hemolytic, which keeps the blood from turning black or brown. S. F. Pellicori also discovered that that the fibers inside the thread were brown while the fibers on the outside were red. Why is this signifcant?
The argument, however, is pointless. The bloodstains are known to be from real blood.