Re: How does Easter Egg dye work on eggs?

Easter egg dye is a form of food coloring. Like most dyes, the chemical 
that does the dyeing is a molecule with two parts. One part gives the dye 
its particular color - red, violet, green, or any other color. The other 
part is the part that bonds to whatever the substrate is, in this case, 
the eggshell. Many dyes suggest adding vinegar because making the dye 
solution acidic helps the bonding part work better. So what happens when 
you dye an egg is that some of the dye in the solution attaches itself to 
the eggshell. This is why a stronger dye solution, or longer time in the 
dye bath, gives you a deeper color - with either a higher concentration of 
dye molecules in solution, or more time for the reaction to happen, you 
get more dye bonded to the egg.