Triplets can be created on any note value. A sixteenth note triplet is three sixteenth notes played evenly across the space usually taken by two sixteenth notes. This means that the triplet grouping lasts for the same duration as an eighth note. It is common for two sixteenth note triplets to occur together as a group of six notes across one quarter note beat. To count a sixteenth note triplet, say Did - dle - a, for two sixteenth note triplets across a beat, say Did - dle - a - Did - dle - a.
Here are some typical ways sixteenth note triplets are used in Blues. Practice them slowly with a metronome until you can play them perfectly and then use the ideas to improvise.
This New Orleans style Blues solo is a real challenge. It contains a new note value - the 32nd note, which is half the value of a 16th note. To hear this style at its best, listen to players like Professor Longhair, James Booker and Dr John.