In this post we will be looking at a technique to use chords from different keys as a way of introducing some novelty or surprise in your chord progression and without having to necessarily make a permanent modulation. We will be doing it by using chromatic harmony.

Simply put, chromatic harmony occurs when the used chords in a given passage or section contain notes that do not belong to the tonality we are working with. The first way you can immediately apply this to your chord progression writing is to simply alter one of the scale tones you are working with and harmonize it.

For instance, in C major, if you choose to lower your fifth degree you will get an F#. In turn you can harmonize it with a D7. Try making a melody over the following chords, but when you use F# in your melody, hit the D7:

| Csus4 | D7 |

The D7 does not belong to the C major tonality and you are now introducing some ambiguity with the use the “foreign” notes suggesting different tonalities. Just be mindful that the extreme use of chromaticism can dilute the sense of key or tonal center by constantly using non-diatonic tones.

Some of the other ways that chromatic harmony can be introduced is by using:

Real parallel chord sequences that have the effect of quickly throwing the music out of one key and into another, even if only for the duration of a few chords and thus contributing to the brief tonicizations:

Chromatic and double chromatic mediants , including voice-leading and chord transformation techniques, as a way used to introduce non-diatonic pitches, suggest different tonalities and participate in the modulation process :

Non-functional chord successions, where functional harmony relationships and cadences are avoided, with unresolved dissonances, tritone relationships and suspended tonality (a moment of unclear or ambiguous tonality):

Equal division of the octave , introducing a symmetric approach to how scales and chords may be built (melody and harmony)

The chromatic chord tones are derived from the equal division of the octave using the C augmented scale

Also see Secondary dominant chords

The tools and techniques to create chromatic harmony do not exhaust here. For instance, and although not with the same premise as modal interchange, we can borrow chords from other musical relationships that can be made with the tonic, like the chromatic mediants relationship.

As an example, we can use a multi-tonic system to introduce chromaticism in a chord progression. This tool maintains a certain tonic relationship with a given key center but in a different way than with parallel modes. Nevertheless, it can also be used to add color to a chord progression without losing the sense of key center, especially if they are not overused.

The developments and practices adopted in post-tonal music do not mean that diatonic chord progressions and other musical devices typical of tonal music stopped being important or used – i.e. chord progressions based on the circle of fifths, harmonic cadences, or major/minor scales.

In fact, although historically chromaticism led to atonality, chromatic tonal music is not the same as atonal music since it does not necessarily avoid the use of materials and devices used to confirm a tonal center.