## Flipping & Flopping: Rookie Question

i've heard arguments for and against (not so much for but i've seen it in practice) that when you create a letter like lowercase 'b' you can use that letter shape to create other letters like lowercase 'd', lowercase 'p' etc...

i sort of figure minor adjustments are necessary in some situations, but i've seen instances where the letter is completely flipped or flopped with no adjustment at all. is this common practice amongst well established and revered type designers? is flopping a 'b' to make a 'd' completely legit? my gut would say no but then i am just a rookie

w|m

Speaking as another rookie:

The easy way to answer this question is to study some well-known fonts. I have just done a test on Univers, where I opened the 'd', and copied the 'b' onto its background. I then flipped and shifted the background, and got a good match. When I did the same test on Myriad, they did not match.

I think that you will find that fonts which have mirror symmetry would normally be classed as 'geometric' or 'constructed', whereas fonts of a humanist persuasion do not have mirror symmetry.

Another test is to take the 'd', copy it onto its own background, and flop it vertically. If you can line up the bowls exactly, then it is probably OK to use mirroring to create other letters. With most fonts, this test will show that the joins between the bowl and the straight are not symmetric about a horizontal axis. The joints on the 'd' are generally pushed upward. This is the case even when the bowl appears to be symmetric. By contrast, the joints on the 'b' are pushed downwards, perhaps to the extent that the bottom joint leads into the straight without the straight touching the baseline.

One technique I think you can safely use, even on asymmetric bowls, is to rotate a bowl to form another letter. In a simple design, you could start with the 'd', and rotate and shift to form the 'p'. You could then take the 'p', and shift its straight upwards to form the 'b', and so on. This would make the ascender and descender exactly equal. In may fonts, the two are not equal: the descender generally being the shorter. Measure some existing fonts to test this.

I hope this helps.