Shevuot 6: Different Shades of White (Regarding Tzara'at)

The rabbis continue their discussion about the identification of tzara'at, translated improperly as leprosy.  They are contemplating what to do when one spot is whiter than another.  Should one be an expert to declare that one white spot is ritually pure or impure?  Can the rabbis declare certain shades of white to be tamei, ritually impure, and others to be tabor, ritually pure?

The example of four glasses of milk with 2, 4, 8, and 16 drops of blood in them is put forward to better explore mixed substances.  Mixed colours would always be weaker than pure colours.  'Snow white' and 'wool white' are both used to describe the pure white colour.

At the end of our daf, the rabbis begin a discussion regarding the potential punishments for forgetting that one is in tumah, a state of ritual impurity, when entering the Temple.