Does making text white (in Microsoft Word) still use printer ink?

White text will not print anything. So what you plan on doing should work relatively well, but the one thing you might run into is alignment of the new print with the existing print on the paper. It should be pretty close, and maybe even right on the money, but if the paper is off just a little being fed into the printer, then the print can be a little high or low from the previous print.