Who’s been poking holes in those flute pads?
(What I have learned about woodwind skin pads.)
How often have you taken a trill key off a flute, or maybe a key off a piccolo, and found a neat hole right in the middle of the pad, pierced by a needle? Seeing this phenomenon makes me think it was done intentionally and consistently, although through ignorance, by a beginning tech. Maybe he or she misunderstood the advice to pierce the edge of the pad to relieve air pressure, or maybe it was done to add resistance to the instrument. If anyone knows a good reason for this, let me know. (firstname.lastname@example.org) I have even seen it on some flutes and piccolos over the years, and even recently on new student flutes.
The previous is an example of leaks that can occur in pads regardless of how well they are shimmed or floated. And it is the kind of leak that is getting more attention now that the magnehelic is being used to find leaks. For sure, if a leak is found under a flute pad that is well shimmed, you will examine the pad closely to look for the problem. If you don’t have a magnehelic, there are methods to help you find these leaks.
Here are some pad related ideas to help solve response problems in woodwinds that appear well padded otherwise.
Cork the end, close keys, and apply suction to entire section with mouth. Release thumb key, count seconds until it opens. Depending on spring tension of thumb key, and how well the thumb key is sealing, 8-10 seconds shows a well sealed flute body. There is a lot of variability in this primitive test. If not, work your way down with the leak isolator from Jim Schmidt. If you suspect an area, remove the key and use a 9/16” diameter short tube to test the pad itself, pressing one end of the tube to the pad tone hole impression, and apply suction with mouth through the other end. Tube ends must be smooth. After testing good pads, you will see how much suction is necessary (a lot). If there is not good suction on the pad, use a Ferree’s long flute key pinning needle (not too sharp) to gently run over the pad skin at like 75 degrees. Be careful, and look closely. If there is a tear or hole, the needle will go right in. Don’t work it too much, though, and ruin a good pad. You need a light touch! Practice on a bad pad. A good skin will let the needle pass around – a damaged or old skin will fail in several places. There may be just one hole or tear, and it may even be under the washer.<> The pad screw may be the culprit. Tighten, and/or insert a neoprene washer under the head. Alternatively, melt a small amount of paraffin next to the screw head to seal the screw. (Put a small bit of wax by the screw head, then pass key over a flame to heat the back of the cup to melt the paraffin. Clean up with Q-tip.) You could also use clear nail polish on the screw head.
On open hole flutes, the bushing may be loose or cracked. Tighten, or replace it – if original is unavailable, use one of Jim Schmidt’s delrin bushings. Test suction again on that pad. Bushing may also need to be sealed with paraffin or nail polish. I hate bushings that have a sharp edge and have cut the pad.
NOTE: It is understood that this suction test does not test all types of leaks. Applying suction will even pull the skin down to the tone hole and seal minor leaks that do need to be shimmed, giving a false impression that the pads are sealing. It is just that if this test fails, even the most meticulous shimming will not seal the leaks caused by the reasons above. So it is used to rule out leaks caused by skin tears and loose screws. And it is easy. These leaks are very common and I have a hard time convincing some people that these ‘unseen’ leaks can have such a great impact. Some new Gemeinhardt flutes, for example, do not play well because the pad screws have loosened. And on the other end – Straubinger pads can have a tendency to tear.
Piccolo and clarinet:
Same techniques, but haven’t used suction on pads – just needle. Tiny holes or tears in pads are very often the culprit for misbehaving piccolos. Also look for splits in seams of plastic piccolo bodies. There can be very small cracks going through the tops of tone holes – fill with super glue. Of course, you have to take it all apart to check the pads, although a skinny leak light does help expose the tone hole cracks. For cheap clarinets, unglued finger chimneys under ring keys may also leak air (but who cares?).
There is a specific problem I have found with Buffet E11 clarinets. The tone holes are razor thin, and when there is uneven wood grain, this produces little bumps/valleys in the rim which are sharp, and cut the pad. This leak is not discovered for months after production. I change affected pads after smoothing tone hole rim.
Bass clarinet and oboe:
Believe it or not, some noticeable leaking can occur through the middle of a cork or synthetic pad that has a central hole for venting. Melt wax in there do not clog hole itself -- seal between the inside diameter of the pad and the central vent column of the key. Also, cracked cork pads do not seal air.
If pad has sewn center, apply melted wax to seal thread and holes. Hold pad slick over flame and melt wax on it, then apply to center of pad.
Pad skin integrity can be assessed by applying water to the pad skin with a water color brush. A waterproof /air proof pad will bead the water up. A porous skin will absorb the water. Tone hole abrasions will show up as dark arcs or spots when moistened. If a sax is stuffy or hard to blow and passes leak light test, start looking for these bad pads. Especially side keys. Even new Selmers from France can have bad hi f pads due to tone hole abrasion.
Alternatively to wetting the calf skin, you can assemble a collection of short tubes of varying diameters to suction-test pads off the instrument, like testing flute pads. I have found 1 ¼” sink drain pipe, vacuum cleaner tubes, and old style metal sax end plugs that are completely hollow, to use for this. You want to match the diameter roughly to the tone hole impression on the pad. Air can pass through the center of a loosely riveted pad. Where does it go? I don’t know, but it still affects the response of a problem instrument.
I share these techniques with the hope that it will help those who haven’t thought of them yet. I give credit to my technical mentors who have helped me over the years.