The Double Thumb Technique
Double thumbing is a slap technique whereby we slap through the string (rest stroke) with a downstroke before using the upstroke to get an extra note in that single motion. So we get two slaps for the price of one!
Before attempting the double thumb slap technique we need to master the rest stroke. This is a name I’ve applied to the technique in order to differentiate it from the regular bounced slap.
To perform a rest stroke, slap the through the string and allow the thumb to come to rest on the next string. The rest stroke provides more fundamental than the bounce and is especially great for playing upper register slapped notes on the D and G string but it’s also vital for performing the double thumb.
Use the following riff as practice:
Octave patterns are a good way of practicing the rest stroke. The action can feel much different to playing with the bounce because the hand is in a more purposeful in-out motion. We slap in with the thumb and then pop out with the finger. The bounce has an in-out bounce motion before the pop.
Applying The Double Thumb
Once you’ve mastered the rest stroke you can bring the double thumb up stroke into play. Simply slap down with rest stroke and then bring the thumb back out, catching the string with the edge of the thumbnail. This is the up stroke.
In the following exercise we have a simple bass line in A minor. In the first example we play all the quarter notes with rest stroke. In the second example we add an extra 8th note to each note play as we bring the up stroke into play:
Double thumbing allows for much faster playing than basic rest stroke would allow. The following exercises can be used to bring 16th notes into our previous line. We’ll add an extra 16th note in each exercise:
Double Thumb Riff
The following riff is made up of a steady stream of 16th notes so we use a constant in-out action with the double thumb technique. There no hammer ons used in the riff. Every note is articulated with the thumb so be sure to focus on consistent time and tone