Pat Missin advice on the use of varnish to stabilize reed action.
I apply the varnish to all the reeds - it's almost as easy to do 20 reeds as it is to do half a dozen. I find that the treatment also improves the bends, especially the upper range blow bends on hgher key harps. I'm sure this is all in the archives, but here goes: Apply the varnish (I'm pretty sure paint and many other substances would do the trick, too. I use bright purple nail varnish, as it is easier to see where it is going.) using the head of a pin (or something similar) - a tiny dab will do the trick. Apply it right in the corner where the playing surface of the reed widens out to form the heel (the bit of the reed that is rivetted to the plate). Try to get it right into that corner, so that it covers a little of the plate, the edge of the reed and just goes into the slot beside the reed. Do the same on the other corner. Don't overdo it. Leave it to dry and then check it. If there is still that dreaded ringing noise, do it again! This does not make the reed easier to overblow - for this you need to adjust the reed gap...

Stephen Schneider and Pete Easton thread on Turbodog tape to stabilize oriental reeds. The first day of the Summit this year, someone asking Howard Levy a question played a (frankly) sorta ugly overblow. "What kind of harp is that?" asked Howard. "A Suzuki ProMaster," was the reply. "No wonder. Suzukis don't do good overblows," lamented Howard. The difficulty of initiating and especially sustaining overbends on certain brands and models of harp has meant that if you played those harps, you effectively had to forgo learning to really play overbends. The world of cutting-edge diatonic harp has been dominated by the Hohner handmade series reedplate, particularly in customized form, because they do overbends significantly better. If you play something else, you're far behind the game. A debated fix for shrilling reed freakout was developed independently by several people a few years ago and can be found in the Harp-l archives as the famous "wax fix" thread. They thought the base of the reed itself might be vibrating at some higher overtone of the note, and stabilized the base by applying beeswax or nail polish, but this never really caught on. At the Summit, Turbodog (aka Dr. James Antaki) tackled the problem of shrilling reed freakout almost as an aside during a discussion of reed/mouth physics. He said harps like LOs suffer from a torsional oscillation of the reed under stress, and that this oscillation could be damped out by applying a small square of tape to the center of the reed's "downwind" side, according to his initial tests.  His fix is actually aerodynamic in nature, and something like it is used to keep bridges from oscillating in high winds--everyone's probably seen the old footage of that one bridge flexing like a rubber band. This vital piece of information was spoken at an unspeakably early hour of the morning to an audience composed almost entirely of Hohner handmade series players, which is sort of like a tree falling in the forest a half mile from someone whose hearing aid is turned off. However, in secondhand form it did reach a longtime LO player who gave it a try (Stephen Schneider) and later enlisted a GM maven (Pete E) in further testing, the results of which shall follow. (Turbodog's a bit busy with his other research interests to pursue it himself at the moment and was happy to depute research assistants.) The method is simply to place a small square of tape at the center of the reed. Shape is important--square (or close to it) does seem to work best. And size does matter; naturally it needs to be small enough that it doesn't overhang the edges of the reed & contact the reedslot. So a square that is slightly narrower than the width of the reed is what to aim for. Too small a piece of tape will reduce the desired effect, while too large a piece--say, a large rectangle--does not help noticeably, though it doesn't seem to hurt either. We have tried plain ol' Scotch tape, Micropore, and my favorite, a 1/16" wide graphic design tape from the art supply store that is easier to cut into 1/16" squares. There are probably decorative 1/16" tapes available at craft/hobby stores, but I haven't checked. The graphic design tape is not terribly easy to cut because the backing is a soft vinylish material and the adhesive itself is fairly thick, but only having to cut it in one direction helps. The adhesive does lend itself to repositioning the tape square on the reed if needed, but stays put when you want it to.  Cut your tape as cleanly as possible so that there aren't frayed edges that could snag the reed in the slot. Turbodog's theory indicated that the tape should be placed on the "downwind" or convex side of the reed, nearest to the reedplate. This complicates installation on the draw plate quite a bit, and means that if you forget about the tape when you regap a draw reed, you can dislodge the tape square and complicate your life still more. Fortunately, installing the draw reed tape on the "outside" still seems to work well at quelling reed squeal, so you don't even have to take your harp apart to install the stuff. Using the standard #11 X-Acto knife blade to do your cutting gives you a handy tool for placing the tape square onto the reed and coaxing it around if necessary. The LO toolkit "gapping pick" is very useful for smoothing down the tape with the outside of its hook end, but as always you can improvise your own tools. As covered in Part 1, Turbotape is a method of suppressing reed squeal by putting a tiny square of tape at the center of the offending reed, which yields nonshrilling overbends and increases the stability of all bends on the notoriously noisy Asian-made reed family.  You can use Turbotape to overbend on any brand of harp, whether you are just learning to do OBs or are already competent at them. Pete E and I have applied Turbotape with success on Lee Oskars, Huang Star Performers and Silvertone Deluxes, Suzuki ProMasters and BluesMasters, Bushmans, and Hohner MS series reeds.  It even helps to stabilize Hohner handmade series and Hering Blues reeds.  The Pocket Pal I tried it on benefited somewhat, but as soon as its reeds loaded up with condensation they began to seriously resist starting overblows--so we respectfully suggest that you pay a little more for your harps than that. We put tape on both reeds in a hole of the Asian-made harps, which can be done without removing the reedplates, as described in Part 1.  This can be done with Hohner handmades or Hering Blues as well, but Pete E had success stabilizing overbends on his GMs by taping only the closing reed involved (1-6B, 7-10D), and I had the same result with my Hering Blues and Hohner handmades. As a less experienced overbender, I found Turbotape to help in initiating overbends, even making previously impossible overbends attainable without modifying the reed offsets.  Turbotape can help make overbends happen at wider ("non-overblow") gapping, especially in conjunction with reedwork like embossing.  Proficient overbenders will find much more stable OBs, if no more ease in initiating them, if Pete E's experience is any indication; these players are already good at starting the note, but can use the easier sustain that Turbotape provides. However, the 1OB and 10DO are not made a certainty by Turbotape, as much as we wish it were; but try it nonetheless and see if it helps you.  Adding weight to the 1D reed seems like a questionable idea, so you might try it only on the 1B at first and see if that makes a difference. Having tried both, I feel that Turbotape is superior to the legendary wax/nail varnish fixes.  The aerodynamic tape approach really does work well and can be applied to a harp without taking it apart, even if wax or varnish stabilizing the reed's base helps the reed in other ways, as Pat Missin notes.  I only had a couple of varnished harps around, but one was a D Lee Oskar whose 3Dbbb still wouldn't behave.  I put Turbotape on just the draw reed, and guess what?  End of problem.  Not an extensive test, but . . . . Drawbacks?  Putting Turbotape on requires a little patience and precision, as do all operations on the reeds themselves.  The tape may possibly dull the reed's tone ever so slightly, Pete and I feel--but we are in firm agreement that the improvement in overbending far outweighs a virtually imperceptible change in tone, especially when you are talking about harps that wouldn't really overbend without Turbotape.  Mind you, we're not even positive that it does change the tone.  However, one thing to watch for is that the tape's weight can drop the reed's pitch by a cent or two, particularly on the higher reeds, so you may want to tune after applying the stuff. I have focused mainly on overbends, but Turbotape also stabilizes bends like the 3Dbbb that can be difficult on LOs, and can let you sustain something like a 10Bbb that otherwise might get away from you.  It can extend your effective range on all kinds of bends. Okay, there you have it.  We haven't tested Turbotape on hundreds of harps yet, but you listers can.  Try it when you get the chance and report back.  If it works for you, use "Turbotape works" as your subject heading, and "Turbotape doesn't work" if that's your result.  Is that a clear enough ballot? :-)  The returns will speak for themselves, we think.