How can my HP print Blue with no Blue Ink?

[strangeproblem]

I tricked my HP to accept a black ink cartridge in the blue ink spot. My printer has No blue ink. I then switched the font on a text document to print blue to actually use and not waste the black ink in the blue spot, but the printer is printing BLUE. Not just a reidual amount but page after page, now over 50 full text pages in BLUE. HOW IS THIS POSSIBLE? The Geek Squad guys are also baffled? Maybe my printer is a miracle and I can sell it for a fortune on Ebay!?!

 

[PhilFrisbie]

You would be surprised how long it takes for the residual ink to be replaced with the fresh ink. . .