Grayscale

Colour that looks clear on screen can turn into indistinguishable mid-greys on a monochrome laser printer, and a chart whose series are told apart only by hue becomes unreadable. Print shops that charge per colour page give a second reason to convert first. Doing the conversion yourself shows you the actual result before you commit to a hundred copies.

Each page is re-rendered at double resolution with the colour removed and stored back as a JPEG image, which is what makes the appearance predictable on any printer. The trade-off is that the page is now a picture: text can no longer be selected, copied or searched, and the document stops being useful as a source of text.

Size can move in either direction. Documents built around photographs usually get smaller, while text-heavy pages typically grow, because clean type compresses far better as text than as an image of text. If the file only needs to be mono for one particular print job, the grayscale setting in your printer driver achieves the same output while leaving the document itself intact.