This article deals with the common problems that one will encounter when the pouches in a player piano are not working correctly.

Without a doubt, the 'pouch', and its associated 'bleed', is the most important and unique part of every player piano system. The function of the pouch is to sense a perforation in a music roll and transform it into a mechanical movement. For a more detailed explanation of this basic operating principle, see "I Love a Player" Chapter 1 -click here.

All pouches are made out of a piece of flexible material, and a variety of materials have been utilized over the last 120 years. The most common material is thin leather, known as tan pneumatic skin, which is fine, chrome tanned hairsheep. Two other popular materials, that were used in the early days of the player piano, are zephyr skin, which is from intestinal membranes, and 0.008"-0.009" thick striker pneumatic cloth, which is finely woven cotton cloth with a coating of natural rubber. All of these materials deteriorate with age in some way, shape, or form, and when they do, they start leaking or they get stiff and as a result they stop working correctly.

In most cases, it's easy to tell when a pouch has stopped functioning correctly because the valve that it is suppose to move stops moving. When that happens, most people, including player technicians, will examine the pouch and/or test it to see if they can determine 'why' it isn't working right. And, if the problem is obvious, they will replace the pouch with a new one. However, believe it or not, the above scenario is the exception rather than the rule, for in most cases the pouch doesn't just quit working. Rather, its performance deteriorates slowly over many years, and when that happens, the resultant action of the valve can be quite erratic and unpredictable. However, upon examination it may seem that the pouch is perfectly fine.