Tongue Blocking Tips - Light Touch, Part 1 (The Bad)
When I was studying Little Walter's legendary blues harmonica instrumental "Roller Coaster," the key moment of discovery in being able to perform the song successfully was in using the lightest touch possible on the face of the harmonica (both the tongue and lips, but most importantly the tongue). This was key in being able to play at his speed and level of dexterity. Here are the negatives of pushing too hard when tongue blocking...
1) Holes to right or left (depending on which tongue block technique you're going for) will unintentionally be blocked. Tone, volume and even pitch (when a hole is constricted, the note being performed can be bent) suffer.
2) Since your tongue is being pushed into the holes, t's difficult to move on the harmonica. Even slight excess push on the face of the harmonica creates undesirable drag as you're moving on the harmonica.
3) A tense tongue is a slow tongue, so even bending, articulations and other tongue movements are labored.
4) Sore tongue from the abrasion of moving on the harmonica and soar auxiliary muscles (neck, shoulders, face, etc.) from this excess tension.
Practice using a light touch this weekend.