Re: What properties in bleach allow it to be colorsafe?

	The key constituent that makes color safe bleaches “color safe” is 
called sodium perborate or NaBO3.  When dissolved in water it produces 
hydrogen peroxide or H2O2, which actually does the cleaning.  Hydrogen 
peroxide has a weak oxygen-oxygen bond and when this bond breaks it 
results in two extremely reactive OH radicals.  These OH radicals each 
have one unpaired electron on oxygen.  It is this unpaired electron that 
allows the radicals to react with dirt and other contaminants on clothes 
eventually degrading them.  Clothes dyes, however, are sufficiently stable 
so that these radicals do not damage them.

Source:
“Boron, Metallo-Boron Compounds, and Boranes.”  Roy M. Adams, ed.  
Interscience Publishers, New York, 1964.