When you are restringing (with new pins) using the original block, do you swab the tuning pin holes with varnish beforehand? (Or dip the pins in varnish before tapping them in?) I seem to recall reading a PTG thread in which a respected tech was convinced that doing so not only made for a consistent-feeling torque, but that over time the same torque was more likely to hold up when using the varnish. If I recall correctly this tech was scientific about recording his torque readings and remeasuring each year for several years, comparing pianos he'd restrung with and without the varnish prep.

For those that have experience with this, any preferred brand/type of varnish? Do you simply apply it with a Q-tip?

And of course I'd like to hear from anyone who thinks (based on real experience) that using varnish is not a good idea.

I'm also curious to know what other kinds of prep or techniques you use when restringing. What kind of prep work do you do with the pinblock, if any? Do you wash the new pins with mineral spirits before using them? Do you measure all pin diameters to ensure uniformity? Klinke seems to be the highest quality manufacturer out there, are there any others? Thanks for your thoughts...

Back in the 70's, when I apprenticed, the shop I worked at didn't varnish the pins/holes - never heard of it before.

Dear James,

I'll be curious to see what others have to say. There are a lot of opinions on this subject.

I have used 'spar varnish' for 30 years in my restringing. A quick swizzle with a hammershank down the tuning-pin hole; a very light coating. I don't let it dry, I swizzle 10, string them, and then hit the next 10, etc. I want the slightly sticky varnish to serve as a 'pin-driving fluid' to prevent damage to the wood of the pinblock as the pin is whacked into place.

Rebuilds where the tech simply whacks the pins into a dry hole always feel 'jumpy' to me. Imprecise and 'clicky', which may get better with time...but often does not.

Using the spar-varnish gives you a smooth and solid feel to the pin. Predictable and nice. It actually improves with time. When I first used this I was not pleased...I thought the pin was lower torque than it should be. It took about a year to understand that the varnish is still 'curing' down there and just got a little tighter as time went by. Pianos restrung with the varnish have remained solid and predictable. It really takes about a year...maybe a year and a half...to see where the torque will finally be.

Not at the shop today, so I can't give you the manufacturer. But, a 'marine spar varnish' is the label.

I look forward to other's comments!

Sipping Costa Rican today,
I am,
In the armchair,

During my university years, I worked at one of the top shops in the country. Using a driving fluid was standard practice there, so it is what I have always done.

However, to take it beyond individual experience, the Appleton Chapter of PTG did a controlled test of restringing with and without driving fluid. In all cases, the results were that there was lower initial pin torque using the driving fluid and a higher pin torque after the fluid dissipated compared to the tuning pins that were driven dry.

I recommend lacquer sanding sealer or shellac over varnish. You really want something that will dissipate more easily. There's no need to have a "coating" on the inside of the pin holes like a layer of finish on the cabinet.

We use a hammer shank to swab the hole before driving the pin. Usually we swab 6 tuning pin holes at a time. More than that and the fluid starts to dissipate or dry. I think using a driving fluid also minimizes/eliminates tuning pins jumping or snapping. It seems to give the pins a real smooth feel as they turn.

There is a bit of interest in this right now, I think there was something about this in the Journal lately. Some of the components of spar varnish (at least the traditional kind) are natural tree resins. I am currently bringing in some some resin from Europe on request from a high profile technician who wants to try it out.

I'd be inclined to think that varnish or resin could work favourably within a certain window of compression/torque on the pin. If the pin hole sizes vary where they get a bit too tight (over 110 in/lbs) I think it would magnify the problem of sticky creepy pins. On the other side of the coin, it wont help too much if the hole is too big to properly hold the pin. Is the application of varnish or rosin meant to compensate for poorly drilled holes as far as size consistancy? I only mention this because I've seen wonderfully responsive tuning pins without the need for chemical additives between it and the wood.

Colophonium or Colophium, (gum rosen) is readily available in N. America. This product can also be used as a hammer hardener for clients who don’t want their hammer sets soaked in chemical solutions such as lacquer or colodium.

In the early 70's I was taught to use rosin for violin bows, rubbed into the pin threads.
Later I was taught and learned by experience that drilling the block correctly gave the best results weather drilling a new block or re-drilling an old one for a larger pin size.
I do not use driving lubricants any longer.
Also, I find that torque alone is not so much of a priority as the feel of the pin moving in the block.

I believe the main purpose of the rosin was to keep the pin from being contaminated with finger oils. It does not accomplish the same kind of thing as using driving fluid which minimizes destruction of the pin hole that happens with the manipulation of the pin during stringing. I believe the use of driving fluid is a superior approach to a superior feel of tuning pin.

Thanks everyone, still hoping to hear from more techs.

Jurgen, I must have missed the article in the Journal. If anyone knows which issue it was in I'd appreciate it.

Just sitting here rebushing a keyset and waiting for the hurricane to arrive....

Actually, kpenbrook, the process of drilling does not leave a fine surface nor one that is consistant in size (incomparison to reaming or boring processes). The hole is nowhere as close to consistancy in size as that pin is on its diameter. The driving of the pin with its lightly threaded surface and the initial rotations to bring up to pitch evens out the walls irregular surface to provide more contact with the pin.... I would regard this as a beneficial thing and not a destructive one, as you mentioned. A few inch lbs of torque might be lost in the process but that is easily compensated for with the initial tool sizing.

I highly suspect that using a driving fluid would interfere with this final sizing of the hole in the same way as using specialized lubricants on an engine before it runs for several thousand miles and the rings properly wear into the cylinders.

Agreed on the drilling.

This was confirmed to me years ago by a long time machinist when he overheard my conversation at a supply house regarding drill bits and what my application was.

The machinist industry does not view twist drills as accurate; twist drills tear the walls of the hole and once that begins there is no way to prevent it or stop it from continuing.

It was recommended to use a Forstner bit for new holes and adjustable reamers or dedicated reamers for the existing holes being enlarged.

Also any liquid that is put into the hole will fill the wood grain making for a more even wall structure. How far it permeates the wood fibers or how long it lasts is the unknown.

When we used rosin, the intent was driving fluid, not protection from finger oils.

I haven’t used any fluids on tuning pins for years now. As you mentioned previously a properly sized hole is yields best results.

If finger oils are a problem for some drop the tuning pins in alcohol or Methyl Hydrate. That’ll clean them up fast.

Just to be clear, I wasn't offering an opinion but experience.

We all know that one way to loosen a tight tuning pin is simply to move it back and forth a dozen times or so. It doesn't matter if you have a "really tight" tuning pin or a "somewhat tight" tuning pin. If you move the pin back and forth several times it WILL be looser than it was. Thus, no real potential for "evening out" the torque from pin to pin.

That is the same kind of manipulation pins get in the stringing process. Regardless of the individual starting torque, manipulation of the pin will always reduce that torque. Always. Addressing variations in hole diameter is a separate issue.

Using a driving fluid has been demonstrated -- by scientific testing and by experience of many top rebuilders -- to reduce the initial wear.

This might be a new concept to some and there certainly are other approaches. I don't really care who uses which procedure. However, there is no question that this approach works and works very well. It has a track record running into multiple decades.

Hmm, different story than what I heard. That is why it was used in some factories.

In any case, the rosin wouldn't do the same thing as the driving fluid because it doesn't dissipate. It stays there -- which may or may not be helpful.

I had always associated rosin with snapping tuning pins. That's its function in a violin bow -- to have that drag and release action that results in the string being activated. However, I don't have any direct experience or awareness of studies or tests one way or the other.

I will add this, there are many top rebuilders that have worked on and improved their drilling techniques such that they do not use driving fluids and track records are there as well.

I am betting that snapping tuning pins are from glazed holes caused by a drill bit being too hot, probably from being dull. Ever notice how they tend to be in the upper end of the piano?

Yup!

High speed glazing is especially problematic with multi laminate blocks( read Delignit) as the resins overheat.

Yep, instead of driving fluid, some of the laminates like delignit could do with a swabbing of acetone when they are done.

Keith,

You speak of driving fluid as something that "dissipates". I presume by this you mean that it is volatile and doesn't leave any solid residues. And yet, you mention sanding sealer or shellac as driving fluids. Both these contain solids dissolved in a solvent carrier. (Just as varnish does.) The solids don't "dissipate".

Could you explain what you mean by a "dissipating" driving fluid? Perhaps a very dilute coating?

People may put other things (or nothing) into tuning pin holes, but the purpose of a driving fluid is simply to lubricate the tuning pin during the time that the pin is actively being manipulated during the stringing process. Any permanent residue is merely incidental -- or perhaps providing an additional benefit.

Varnishes are slow drying and have a high solids content. As a general category, their films also tend to be softer and more flexible than lacquers or shellac. In other words, a potential for a more "gummy" kind of end result. I am not aware of any studies comparing varnish and other products as a driving fluid, but its properties are welll-known and that would be my assumption about using varnish.

You are right, of course, that there is "something" left behind -- otherwise why not just use whatever thinner is the vehicle for the finish? But lacquers --as a category including sealers-- (followed by shellac dissolved in alcohol) is recognized for both for its low viscosity and its volatility; particularly in comparison to varnishes.

The effects of these two qualities is recognized by refinishers: If you apply lacquer sealer or shellac to the end grain of wood, it will be observed to
1) soak into the wood with little residue evident on the surface, and
2) dry very quickly.
In comparison, varnish will leave somewhat more of a film and take longer to dry.
There is no reason to suppose that the variation of those qualities between the lacquer-type category and the varnish category changes merely because it is happening inside a tuning pin hole.

In practice, the use of a driving fluid (I use lacquer sanding sealer and a few mililiters will do an entire piano) does lubricate the pin hole for a few hours, with the greatest effect within the first 20 minutes. As I mentioned, earlier, it also does seem to make for a nice "feel" as well as a higher final torque, so no doubt there is some effect of the solids component remaining in the hole, but it is not the primary reason for using the fluid.

As has been pointed out, there are other parameters to consider when drilling blocks and I don't suggest that driving fluid will somehow magically fix some major blunder done in another part of the process.

Having done it with and without driving fluid, I can say I prefer the use of the driving fluid. However, I don't suggest it is essential and realize that there are multiple approaches to doing high quality work. It may be that those other approaches involve a higher risk of carpal tunnel syndrome and the like . . .

'Interesting thread. I've used Delignit material since 1978 (if memory serves). Initially I tried many different combinations of drill sizes, drills, several varnishes, powdered rosin, nothing on the pins, and even pointing the pins to all four points of the compass before driving. Tentatively, I finally settled on something that seemed to yield the most consistent results with a twenty five year track record - careful and consistent drilling with a cold air stream on a really good letter size "H" fast spiral drill. I use powdered rosin on the pins, but that may be a little bow to voodoo hoodoo.

Now I get to start all over experimenting with a Boulduc block. Yippie!

If you are going to try a new block, I recommend the Falconwood -- now sold by technicians based in Milwaukee. It's a stronger block with a higher friction ratio than any other block -- thereby requiring less stress on the block to maintain a given torque -- and there has never been a failure since its introduction about 50 years ago.

For Falconwood, you only need an "I" drill bit using your same drilling protocol.
I use driving fluid.

Going for a new block I would recommend the hybrid, designed by Ron Nossaman.
A custom 9mm Dilignit cap (not bridge capping or pin block material) on a standard multi-lam block.

My rebuilder has been using the Falconwood pin block exclusively for many years, with not one failure. I have one in my M&H RBB.

He did mention to me once, that it was important to use a new drill bit with each pinblock....I suspect this is the case when drilling any pinblock?

I bore twice, taking out about 1/2 the wood with the first bore using a bit I can sacrifice, and then boring to final diameter. Heat builds up when the chips cannot escape faster than they are generated, so taking out a bunch of wood first keeps the second bit from overheating, and it can be reused several times with only a bit of honing.

I've found rigging up a stream of compressed air on the bit while drilling keeps it cool. I use even pressure on the bit, so I progress faster in softer areas of the block and slower in harder areas. I've never used a driving fluid - dry pins have been fine. I keep my fingers off the threads of the tuning pins, so no issue there - (I use a string coiler). The only issue with sticky pins I've had was this old Lester grand, where budget forced me to keep the same pin block. The old, loose pins were sticky, and the new, larger pins were just as sticky.

I wonder if some of those lovely feeling Indonesian and Chinese blocks are varnished up during stringing. My restrings don't feel like those do - never have.......

Another consideration is ambient RH when drilling. If the RH is 20% due to cold winter air, a good feeling block can be way too tight when it gets to humid Florida where the average RH is 55%. Dealing with tight pins is common here.

I agree about two passes. The second will get rid of any errors made on the first.

I once re-drilled an existing block for oversized pins. I ground off the cutting edge of the bit, let it pull itself into the hole, held it in place and spun the drill to let the flutes do the cutting. It came out ok.