Some thoughts about pads

First, two things on which all the following is based.

(a) "It's good enough at present" is not good enough.

(b) An additional thought on the subject of woodwind instrument pads goes a bit like

this:

In about 'Seventeen something' it must have dawned on some smart-alec that the six or seven holes drilled in the side of the tube down which he/she blew in order to make music, had to be in places that ones fingers could reach and be of a size that fingers could cover. Oh, & there really needed to be many more holes than the available number of fingers!

It meant that the existing holes couldn't possibly be in the right place or be of the right size acoustically. And so key-work mechanisms came about in order to remotely open & close larger holes in places the fingers couldn't reach & this in turn required the invention of a resilient pad of some sort in order to act as a valve-cover on the holes. Apart from the early attempts using leather on a flat paddle-like key & pewter pads, the most effective solution, taking into account the fact that the pad had to be fairly compliant to accommodate the poor mechanics of the day & also relatively quiet in

use, was to use a soft bag of horse-hair which might mould itself to the shape of the hole it was intended to cover. And over 200 years later, what is it we use in our modern instruments??.......... a bag of horse-hair!!

Well okay, it's slightly more sophisticated in that it's a disc of felt covered by a animal skin now but does that really represent a couple of hundred years progress?? In medical terms 200 years ago, the doctor would be saying “Right sir, we're just going to strap you down on this table, stuff a piece of cloth in your mouth to stop you screaming too much & then saw your leg off”.  Today, the doctor would say “Oh no sir, we don't do that any more. It's what we call key-hole surgery these days. You can go home in a couple of hours”.

Ah well, they'll probably be advocating Dinosaur Skin Pads next!!!

Now, given the above & ignoring for the moment all the synthetic pads that are or have been used, the overwhelming type in use is still that of an animal skin  wrapped round a disc of some type of compliant material, usually a felt of some kind. This makes sense after all as it's what your fingers are & what the pads are trying to replicate when opening & closing the tone-holes.

 Unfortunately there are a couple of problems!!

One is caused by the fact that in pressing a key, particularly on the (now) closed-hole system instrument, that key has to depress another one or two keys at the same time. Which means that not only does the player feel the compliance of their own finger tip, but also that of the other three keys as well, along with their various interlinks & imperfect semi-reactive materials from which they're made.

This is rather like a pianist being able to play a chord on a piano by pressing one key only, the other keys  not only interlinked mechanically but each key also having its own compliant, independent  semi - reactive  interface. It would be as if the pianist had limited, imperfect co-ordination of their fingers so that instead of the notes within the chord being struck simultaniously, each note is sounded at a slightly different time, which equates to bad technique on a piano but results in a squeak or 'non-note' on a wind instrument.

The  mechanical interlinks can be pretty successfully sorted with some reasonably good engineering but the 'semi-reactive materials' part is a bit it more of a problem.

There's healthy debate as to which animal skin is better for making saxophone & bassoon pads & somewhat less so, as to which gold beater's skin (intestinal skin) is better for clarinet & flute pads. I think it's universally accepted that oboes use cork pads, & the reason they do is a very, (repeat very) big part of why I believe there to be problem with skin pads!

 It's an indisputable fact that skin has evolved over hundreds of millions of years to function as the epidermis of virtually all living things on the planet. I can't think of any exceptions off hand but this isn't a biology lesson anyway so not to worry if there are some.

It's also indisputable that it's evolved to do the job for which it was specifically intended & not as a material with which to make pads for musical instruments. We use it for many things but that's not what its fundamental use is/was.

So skin is skin basically & its main function is to act as a flexible, stretchy, very reactive covering to keep the inside in & the outside out.

While that basic function is the same, the difference between the various types of skin is relatively small. Yes there are different properties to be used/exploited by choosing to make something from cow hide, crocodile skin, shark skin or any other skin. It's true that the hide from an animal that has for generations lived at the top of a mountain for instance or in the far North or South has a slightly different hide to that of one from the bottom slopes of the mountain or the Tropics.00

But these differences, as far as musical instrument pads are concerned, are pretty small.

Before trying to determine which materials might be more suitable, & therefore the properties which make the existing materials less than suitable, let's just make sure we understand one thing - it's this.

All materials move, either a lot or a little, under the influence of temperature &/or humidity changes. Further, all materials which are either formed or forced into a position other than their natural state will, in part at least, try to revert back to that state over a longer or shorter period of time.

To give a couple of examples in musical instrument terms, the metal of the tone-holes formed by the harsh process of drawing them from the body of the saxophone will, over a number of years try to slowly sink back down, not uniformly I'm afraid, which is why they become distorted & people spend a lot of time & money re-flattening the tops of them. Or, more importantly, the crease forced into each pad during manufacture or subsequent repair by the use of heat & pressure to form what is referred to as the 'bedding ring' will partly come out rather quickly in it's desire to get back to nature, which is no surprise as it's pretty clear what happens to any crease which is ironed into the material of a garment  & then subjected to an atmosphere of warm, damp air.

 This is what spurs me on to try to find materials whose list of properties better fit  the requirements for the job. Remember that by definition, a pad is going to require a mixture of opposing properties & however many different materials this takes, they must fit into a thickness of not more than 4mm-5mm at best.

Anyway let's not think of them as a pad anymore, let's call them a valve, which is what they actually are, albeit a rather poor valve in engineering terms, but that's because they have other things to do as well. They have to be relatively quiet in operation unlike the metal to metal valve of a combustion engine & it's impractical to use a heavy return spring or radiator type tap.

To do it's job properly the valve/pad in a musical instrument must therefore contain both reactive & non-reactive elements.

As previously stated, all materials move for one reason or another but for the purposes of this diatribe, let's assume a thick wire hawser to represent 100% non-reactive material & a bungee to be very reactive, & in between those two extremes all materials will display varying reactive properties.

In a normal leather pad today the disc of felt inside has to act as the most reactive part so as to remain as quiet as possible. The softer the felt the quieter the pad will be. But  the softer the felt the less accurate & less stable it is & it will convey a spongy feel to the player. Also, it must be stiff enough to withstand the inward pull of the leather tightly wrapped around it! So these opposing requirements will have to be taken into account when choosing the type of felt to be used be it  interwoven, pressed felt & of course the type of fibre from which it's made.

The leather or skin on the outside wrapped around the felt seems on the face of it to be a good choice of covering material. It's semi-reactive & can be treated to make it pretty waterproof & whilst it does well to retain a crease, particularly when it's used to cover a firm material as in say book binding, it's ability to keep that crease is heavily compromised when used to cover a soft, very much more reactive material. It is, like everything, influenced by temperature changes but more importantly, because the felt inside is having to hold it out & stop it collapsing inwards, two things are happening.

The felt is being asked to do two directly opposing jobs at the same time. That is, act as a resilient medium under the leather & keep its shape too. Both jobs are compromised somewhat in the same way as the front wheels of a front-wheel drive car are asked to drive & steer at the same time & the two requirements can be better accomplished separately.

Secondly, as a result of this compromise, the surface of the resultant pad is neither flat nor consistent in texture across its surface. To use the book-binding analogy again, it gets firmer & firmer towards its outer edges (i.e. towards the binding as opposed the the open pages) which are now, because the skin is pulled round, moving away from any flatness the pad may have.

This means that on keys where the cup & therefore pad is not central to the tone-hole it's covering, or even more commonly, where the cup/pad diameter is only slightly bigger than hole it's trying to cover, the tone-hole rim is trying to bed/seal on a surface which changes in consistency around its circumference &/or is moving away from it. And therefore because each part of the pad at the tone-hole circumference has a different consistency, it moves differently & at a different rate under humidity & temperature influences, plus any effect on one part of the surface not only affects that place but as it's a skin, other surrounding areas will be affected. Try touching a screwdriver blade on the surface of a pad & see how it not only distorts where the blade is touching but pulls the skin over quite a wide area of the surface as well.

All the above applies to clarinet & flute skin pads to  a greater or lesser degree & the negative influence of all of the problems outlined can be multiplied ten times in the case of the smaller instruments - Piccolo, Soprano & Sopranino Sax & Eb clarinet.

The separation of these two conflicting functions has in part been overcome by the original American Conn Saxophone Co's 'Resopads'  in the 40s & 50s & in modern times by Mr.Straubinger's Flute pads both of which use a similar solution.

As stated earlier, Oboes overcome most of these problems by using cork pads. So why is this & why can't they be used on other instruments successfully?

Well cork is relatively non-reactive & is a hard & stable enough material to accept & retain the very fine inter-keywork adjustments necessary on the instrument. Further, the body is quite small & therefore requires only small keywork movement & so the noise problem which would be experienced on a larger instrument is averted.