I am really struggling on my scales that contain most of the black keys (BM, g#m, etc.). I can play the notes just fine, but my thumb is always breaking the line (sounds like thumping). Does anybody have a suggestion for how to fix this?
Thanks for taking the time to ask an excellent question, Danny, and it turns out that "thumping thumbs" are a common problem in scales such as B, F sharp, and D flat majors, as well as B flat, E flat, and G sharp minors.
First of all, a short physics lesson. In the workings of levers, the longer the lever and the farther towards the end of the lever the force is exerted, the more optimal the force will be. Similarly, with a shorter lever that is depressed slightly away from the end, the less optimal the force will be. This corresponds to the thumbs hitting the ends of the white keys compared to the second, third, and fourth fingers that hit towards the middle of the black keys.
In the black key scale fingerings, the longer second, third, and fourth fingers are playing the black notes, while the limited number of white notes are optimally played by the shorter thumb. In the six keys above, the thumb plays nearly all the white notes. In addition, the way that most pianists learn those scales is by learning which notes the thumbs play, then using them as an anchor to navigate the minefield of black keys that make up much of the scales, resulting in the thumping you mention.
I think that overactive thumbs in these scales can often be a leftover from the initial stages of the learning process, and that once you reach fluency, you then need to "iron out" the louder thumbs.
There are several ways to do this:
1. Given the laws of levers applied to playing scales with mostly black notes, even force applied to all the notes will result in the thumbs playing louder. Therefore, play less on the white notes your thumbs play in order to even out the sound.
2. Be aware of how much wrist and forearm motion you are using when passing the thumbs under. Many pianists utilize a slight jerk of the wrist or forearm when passing under the thumbs, resulting in an accent. Although teachers differ the subject, I believe that the wrist and forearm should be quiet during the carriage of the thumb under the hand. I also ask pianists to smoothly and gently move their forearms back and forth up and down the keyboard as a template for a smooth motion. Then when you play the actual scales (and arpeggios too!), try to keep the smoothness of motion in your forearms. Many pianists that utilize this concept also mention that it feels like they are "leading" with the forearm when playing scales and arpeggios.
But most importantly...
3. Let your ears be your guide. Every scale will require slightly different angles and speeds of attack to achieve a flawless sound, so rather than worry yourself with the above physics lesson, listen like a hawk. Work with your teacher to develop a sound ideal for your scales, then apply it to all the keys, working on really listening to every sound you make in order to even out each key.
Best of luck with the treacherous black key scales, Danny, and may your hard work help you achieve technical mastery at the piano!