What are the different ways of adding non-diatonic chords?

Question

I'm trying to add more detail to what I'm playing by using non-diatonic chords. So far the main ways I have found are: 1. Borrowing chords from parallel key (mode mixture) 2. Chromatic Mediants (playing major chords that are minor thirds apart from example). 3. Using Secondary Dominants. Are there any other ways?

Answer 1

Diatonic chords are minor and major chords as diatonic scales separated from chromatic. So diatonic chords belong to diatonic scales and that also includes diminshed and augumented chords such as III+and vii°. Borrowed dominants are major chords so they are diatonic as well. By definition non diatonic chord is a chord that contains one or more notes from outside that scale, but also this non-diatonic chord still contains at least one note from that scale. I hope that helps.