[Harp-L] Sticking/Popping valves, long

["Vern Smith" <jevern@xxxxxxx>]

I received and lost an offline message inquiring about sticking-valve remedies.  Here is the information that will answer his questions and will, I presume, henceforth reside in the harp-l archives.

I recommend a combination of remedies, any one of which may be sufficient to solve the problem under a particular set of circumstances.  However, I am a belt-and-suspenders kind of guy.  The remedies are:

1. Warming the harp to about 100 degF under a heating pad before you begin to play.  This reduces the extra condensation that occurs when you start with a cold harp. It does not eliminate the condensation that occurs under steady-state playing.  Heating pads can be obtained at your local drugstore for about $20.  Many players, including chromatic virtuoso Robert Bonfiglio, use this remedy.

2. Engrave a groove in the reedplate where the valve touches and parallel to the edge of the slot.  I use a General brand carbide-tipped scriber that looks like a knurled aluminum pencil. 
These are available in the Sears tool department and at your local hardware store.  On the net, see http://www.mcmaster.com/ part # 2157A11, $4.35.  Do not smooth or sand the engraved groove.  The raised burrs along the edges of the groove, not the excavated groove itself, serve to reduce tha area of contact between the valve and plate.

For my own use, I made a steel guide that fits in the slot and provides edges along both sides and the end of the slot against which the scriber can be moved.  From this I have molded a number of polyurethane replicas that can be used for the same purpose.  If you will send your snailmail address to Vern Smith, 3424A Calle Azul, Laguna Woods, CA, I'll send you one free.  The plastic should last long enough to do several harps and will give you the idea how to engrave and/or make your own guide. It is possible to engrave freehand.  No warranty or guarantee of results....use at your own risk. Practice on a junk reedplate before working on your functional instruments.

3. Apply wax to the reedplate where the valve touches.  Then polish it to a hard shine.  Do not apply it to the area around the rivet where you will glue the valve down.  Paste auto-body and floor waxes, sparingly applied, are recommended.  Parafin, candle, bee's, crayon, and other soft waxes are questionable.  I apply it with the tip of my little finger, wait a few minutes, and polish with a cloth or paper towel wrapped around the same finger.

Why do I think that these remedies work?

1. I have never failed to permanently* fix a popping valve by removing it, engraving and waxing the plate under it, and replacing it with a teflon valve.  *well...at least for a very long time.

2. I recently measured the force required to separate a "sandwich" of wet teflon valve material between a pair of one inch square aluminum blocks. I tested all 4 combinations of scribed/unscribed and waxed/unwaxed surfaces on the blocks.  Both scribing and waxing greatly reduced the measured force and when both were used, the force was too small to be detected by my rig.  I'm sure that other's could find defects in my test methods, but they convinced me.

I placed the sandwich on a postal scale and slowly lifted the top block by an attached string. I pulled until the sandwich popped apart. If the minimum scale reading was less than the weight of the parts remaining on the scale, I attributed the difference to the surface tension of the water.  I encourage all of you to repeat my experiment to satisfy yourselves that it is or is not valid, then report your findings.  

Am I the final authority on sticking popping valves?

NO!  However, I am confident enough of these remedies to share them with other harpers.  I encourage you to report your experience, any problems or failures, and results using them.  YMMV.  IMO, sticking/popping valves is the most serious detriment to happy enjoyment of this wonderful instrument.  We should all cooperate in finding and applying effective remedies.

Vern

Visit my harmonica website: www.hands-free-chromatic.7p.com