The logic is to consider it like a Birthday Cake:
I just did an anti-witness on this subject using the chart and the KM and my results were as follows MOL
A normal person would assume that if we are forbidden to eat a cake, then we are forbidden to consume the ingrediants that make up the cake.
A well-programmed JW will insist that it is not the cake we are forbidden to consume, but the meaning behind the cake and therefore we are permitted to eat the flour, water eggs etc. Since blood is 90% water and Jesus served water then we are able to consume the ingrediants? (the part about Jesus is mine by the way)
Now here is how to make them shut up: Ask how the Red Cross gets the components. They will assume that there is a specific operation to seperate them and that is correct. Ask but HOW does the RC get the blood? They will act unsure and mumble about dead people or donations. Now what does Leviticus 17:13 ? say? Here is where they either admit that the WTBS is breaking God's law by using products that should have been covered with dirt, or they have to admit that Leviticus talks about Jewish dietary law. There are only the two alternatives when one actually uses the scripture rather than broken fragments as the WTBS does.