The pentatonic scale is a wonderful invention for guitarists — and can save you from sounding bad during a guitar solo. On the flip side, because this is such a "safe" scale, it can lack color or teeth. You can add some blues bite and grit to the minor pentatonic scale by throwing in the interval of a flatted 5 — Bb in the key of E minor. The new six-note scale, appropriately called the blues scale, is tailor-made to bring out the edge in blues.
The following figure shows the notes and pattern of the E blues scale. Play through the scale slowly from bottom to top and then from top to bottom, one note at a time. Pay special attention to where the added Bb comes in, and notice how it reeks (in a good way) with blues flavor.
Thousands of songs use the blues scale, both in their composed melodies and in their improvised solos. Some famous rock songs, such as Cream’s “Sunshine of Your Love” and Deep Purple’s “Smoke on the Water,” use the blues scale as the main riff of the song — and exploit that flat 5 interval.
Although the following melody may not be as immortal as "Smoke on the Water," it uses the blues scale as a melodic solo over a 12-bar blues in E and gives you an idea of the type of flavor this scale can add to your guitar playing.
