Using the “bold” button or keyboard shortcut is certainly safe to do in modern design applications, as long as you know which weight your font is going to “bold” to. In simple two-weight fonts, a “regular” weight becomes “bold.”
But in font families that have multiple weights, the “bold” version of a weight is often two or more steps thicker than the original. (Helvetica Neue, Futura, and many of the Adobe “Pro” fonts behave this way.)
This system makes sense, because the next weight up may not be visually different (bolder) enough from the original. So, the font designer decides which weight is visually “bold” enough to link to each weight.
When in doubt, select fonts by weight, define a Character style for that font, and assign a keyboard shortcut to the Character style for easy styling!
Jay Nelson is the editorial director of PlanetQuark.com, and the editor and publisher of Design Tools Monthly. He’s also the author of the QuarkXPress 8 and QuarkXPress 7 training titles at Lynda.com, as well as the training videos Quark includes in the box with QuarkXPress 7 . In addition, Jay writes regularly for Macworld and Photoshop User magazines and speaks at industry events.