The damper of the piano is part of the mechanism that stops the strings vibrations, which of course stops the sound. If it were not for the damper, the sounds produced from the piano would continue longer than wanted. When a violin player wants to stop the sound, the process is a simple one; the player just stops drawing the bow across the strings.
The continuance of the tone, in the case of the piano, depends only negatively on the action of the damper. Positively, it depends on the vibrations of the strings, assisted and reinforced by the large surface of the sounding board, over which they are stretched. The key, as long as it is kept down by the finger, exercises a restraining influence on the damper, and the finger may therefore be considered to have some slight extra resistance offered to it by the weight of the damper. If this resistance were great enough to be perceived by the finger while keeping the key down, some extra force would be needed to counteract it; but as the weight of the hand and arm is more than adequate to resist the weight of the damper, added to that of the key, no extra pressure on the piano key is necessary to keep the damper away from the string. The hold that the hand keeps on the key after the push, must be accompanied by no continuous clinging pressure, as this after pressure destroys the looseness or elasticity of the muscles, and makes no greater impression on the damper mechanism, than does a hold of the lightest and loosest description.
The finger work consists of two elements, namely, the push, necessary to make the hammer strike the string, and the hold, necessary to prevent the damper from stopping the tone. The impulse used in delivering the push should always be of a momentary duration, as the work done by it, namely, the hammer stroke is instantaneously accomplished. The speed used in delivering this push varies, depending on whether a loud or soft tone is wanted. The push ought never to be accompanied by any feeling of strain in the hand or arm, however loud the tone, or long continued the passage to be played, may be. If a strained feeling accompany it, the push has then been made faulty as a real impulse is, strictly speaking, too short lived an action to leave behind it muscular exhaustion. The second element in the finger work is the hold.
This, for want of a better word, must be taken to signify the keeping down of the key by the finger after the push. It consists of no impulse, nor pressure, nor grasp, nor anything else which could mean forcible expenditure of strength. It must consist only of the most studied inactivity of arm and hand, and is thus the opposite of the push. Clinging tightly to the key after the finger is down does the greatest harm to the hand, and is an instance on the piano of that superfluous energy which accomplishes nothing artistic.
The hold must be dissociated entirely from every idea entailing rigidity of hand or arm. If the piano student will devote a little time to learning and mastering this important piano technique, then he or she will make playing the piano look easy, and that is a skill in itself.
Michael David Shaw is a keyboard and organ teacher. He has written an easy start music eBook especially for beginners simply called "Lesson 1" You can download this Music PDF at http://www.mikesmusicroom.co.uk and http://www.keyboardsheetmusic.co.uk