I have volunteered with our local Blood Bank for many
years. Even with much care, some blood drops onto the
donors, and is taken out with, first, peroxide. It is wet and
patted with a rough cloth/paper and done again. If that
does not work, then the heavy stuff is brought in and used,
plain old diluted bleach. It is about a ten percent bleach with
90 percent water. When the blood is gone the bleach is washed out with clear, cold water.
Hope this helps..