Wednesday, August 1, 2012

Leonardo daVinci Painted with lead paint

I am confused. On the History channel last night I watched a program about Leonardo daVinci and his secret messages in his paintings 

At one point they showed a painting started by another person that Leonardo completed. Leonardo added an angel to the painting, using paint different than the original painter.  The program questioned why Leonardo would have used a different paint.

Leonardo used a lead based paint to paint the angel.  The original painter had used some other kind of paint.  When they did an X-ray of the picture that is done to see what is hidden behind the paint, Leonardo’s angel disappears.   

My question, my confusion, is because I understand that lead blocks or absorbs X-rays.  How does the X-ray see behind the lead paint to the scene behind the angel? Why does it disappear?  Am I missing something?  I would think the lead would keep the X-ray from seeing behind the angel. 

Can anyone answer my question?