The mystery about pads!
What difference does the pad make?
The purpose of the pad is; to seal off the tone hole when closed; and to reflect the sound-wave back into the instrument. The first criteria has to be a given, otherwise the instrument can't function properly, but the second point opens up a range of subjective discussions about the "best" type of pad to use. Ideally the pad needs to sit flatly across the hole with just a small indentation embossed into it, to create a good seal where it contacts the rim of the hole. The core of a pad is usually a wad of high-density felt covered with some kind of air and water-tight membrane stretched across it. Most commonly this air-tight covering will be made of 'skin' or leather. There are, however, some pads made of other materials, like Goretex, cork, or synthetic rubber/foam type materials. The differences noticed are, the ease with which the pad fits, or in some cases almost grips, the top of the hole and the qualities of the material across the hole, which will affect the resonance, response and tonal qualities of the instrument.
Below is a description of the most common pads used for each woodwind instrument and their affect on tonal and playing characteristics. One aspect of choosing a pad that is often overlooked, is that every material has an absorbent coefficient, which is basically the properties of a material to either reflect or absorb sound frequencies. The material covering the pad on your instrument is no different and will partly be responsible for the character of the instrument in terms of the sound and response that the instrument possesses. This effect is achieved by a combination of pads reflecting and absorbing partials in the sound wave as it travels down the tube. Interestingly, in recent years the manufacturing of larger saxophone pads has evolved into a fine science, as more subtle choices with the shape and material of the central reflectors are now available, whilst harder and thinner flute pads have also evolved.
Over a period of time pads will deteriorate, either by losing their shape, or by ceasing to be air-tight. This is caused by a combination of continual pressing against the tone-hole and continuous moistening and drying through regular use. Pads that lose their shape are no longer flat where they cross the center of an open hole and will sink into the tone hole as they cross it. This will affect the overall resonance, as the reflection of the sound wave and tonal spectrum becomes affected. For traditional skin or leather pads, after prolonged use, as a consequence of absorbing moisture, or becoming wet when water seeps through a tone-hole, the covering can become brittle, or in the case of leather -rot, and will subsequently crack. This will allow leaks through the pad itself, causing the instrument to play with increased resistance and start to `fight back'. Cork pads are also particularly prone to going out of shape, as cork is a porous material. Synthetic and Goretex pads mostly don't suffer from these issues, but have other considerations when it comes to the tonal qualities offered.
I am often asked to advise which type of pad should be fitted to specific instruments. and although I might have my own preferences, I prefer to ask the player how they would like the instrument to sound and feel. I would normally fit the same type of pads as those that come off, but the final choice in this is subjective and each player, as they become more experienced, will eventually work out their own preference. One thing is clear however, despite what many technicians say, different types of pad do create different kinds of response and encourage a different harmonic spectrum in the tone of an instrument.
The evidence for this has been experienced for many years with basic modifications in design and factory set-ups. For example, as mentioned above, saxophone players have become more aware of the difference in the variously shaped reflectors on the market, whilst most experienced flute players prefer to play an open-hole flute, where there is no pad at all covering the center of the key. At its simplest, a harder pad will tend to encourage response and reflect higher frequencies back into the instrument, whereas a softer pad will tend to "soak up" some higher frequencies and can slow response. The ensuing tone and response of each instrument is a subjective matter, but the final choice will be a combination of the absorbent coefficient of the material used and the pad's ability to stay in shape.
For clarinets, the traditional choice has mostly been between a harder 'skin' pad, or a softer leather one. It was once thought that the 'skin' used was fish skin, but received knowledge informs me that they are made from a thinned form of sheep's intestine (not good for vegan players). All good quality 'skin' pads should have a double-bladder construction, i.e. two layers of skin, and "deluxe" leather pads should be backed by a polythene layer, making them as impervious as possible. Leather pads are most commonly finished in white or tan colour.
Fitting skin pads is always best left to a professional technician, as there is little give in them and no room for error! Once fitted the skin pad tends to encourage a more immediate response and a brighter, more projecting tone. (I generally fit skin pads to most continental makes, unless directed otherwise). Leather pads can be the preferred choice of many technicians as, being softer, they are easier to fit and mold to the tone-hole easily. Traditionally leather pads were fitted to Boosey and Hawkes instruments, and several contemporary models still use them.
One note of interest is that Buffets now fit Goretex pads. This is basically a layer of Goretex (an artificial leather- type substance) over a skin pad, which is supposed to make the pad feel more firm. The Goretex layer does result in a nice tight seal to the tone-hole and are quite firm, giving a good reflection to the sound wave, but one down side is that they are, unfortunately, very expensive and not easy to source. Suppliers usually list then in their catalogues, but don't actually have them in stock!
Leather pads do encourage a more rounded, mellower sound, due to the absorption of some higher partials in the tone, which many players prefer. These can however, result in a more resistant response depending on the design of instrument. Some players have experimented further and like the feel of cork pads. Cork pads do have the advantage of having a hard surface and are long-lasting, but cork is also a porous material, making it more challenging to get the instrument air-tight and, as highlighted above, are prone to going out of shape if water drips onto them. I do, however, fit a cork pad to speaker keys by default, as they survive longer against the sharp edge of the speaker-hole bushing. 'Superpads' are made from a covering of some foam-type material (I don't know what) over a cork base. They 'grip' the tone-hole very efficiently and produce a solid air-tight joint, they are, however, made from a soft material and can leave the instrument sounding darker.
In the case of flutes, pads of differing thickness and hardness are available and they are most commonly finished with a skin covering. Thinner pads tend to be harder and hold their shape longer, though the density of the felt core can vary with different makers. Myazawa flutes use Straubinger pads, which have a metal backing and a very thin felt cushion behind the skin surface. This results in a long lasting pad which holds its shape well, though players have criticized how noisy they are. Unfortunately, at the time of writing, Straubinger refuses to sell these on the open market, making it impossible to replace like with like. Muramatsu has developed its own pad, virtually a copy of the Straubinger, which are, similarly, not available to buy. For these instruments I use the hardest pads available in standard production. Most common for other flutes are yellow-skin pads, waxed to last longer and repel moisture, with various thicknesses available. I always match the manufacturer's specification. Pads required for open-hole instruments are especially cut and therefore more expensive.
Until recently all saxophone pads have been made using a leather covering, though recent experiments using Gore-tex pads have been tried. The main differences in standard saxophone pads are the thickness of the pad and the material and shape of the reflector. This is the disc rivet at the center of the larger pads, needed firstly to hold the middle of the pad in shape and secondly to offer something hard for the sound-wave to reflect against, hence the name. These will either be made from plastic or metal, shaped like a dome or with a convex profile. Unless instructed otherwise, I will replace pads with the same specification as those that come off (Yamaha's have plastic pads fitted in the factory, Selmer's use metal with an embossed ring). New to the market are Roo pads, made from kangaroo skin with a multi-faceted metal reflector finished with a choice of silver, brass, copper or gold plating. The Roo leather is remarkably tough, even cutting it with a razor is challenging! As a result they will probably last longer than the traditional calf or goat skin pads. Roo leather is thicker and softer in its density, and the modified reflectors offered, aim to restore a responsive feel and brighter sound. Note - they are also very expensive!
Oboes have always used a combination of cork and skin pads, the mix of this combination varies between manufacturers but I will normally replace pads matching the type which is removed.
Bassoons will require leather pads because of the size of the cups used. Traditionally goat skin is usually selected, as it is thinner than calf skin and more suited to the maple wooden body and they are stained white. After fitting though, the technician should proof the center of the pads with wax, this repels moisture and helps prolong the life of the pad.