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I used to use soapstone all the time before teflon became available. Used a "welder's marker", 1/2" x 1/8" x 6". Rubbed it on felt, knuckles, etc.

Yes. I rubbed soapstone on my sandstick to make a powder which I would apply to knuckles. It produces a "silky" feel which is slightly different from PTFE. I think PTFE is slightly lower in friction.

I've ordered some WS2 (Tungsten DiSulfide) to try. There's a firm in Canada that has it in bulk but shipping cost is a real hit.

This is the first I've heard of McLube Sailkote, so thanks Roy. From what I can find on the internet, it seems to be much slicker than PTFE in boating applications, although I read that some think it smells funny. So, does it really smell that bad? Seems it's universally better than PTFE, but I've read elsewhere on PW that some have found PTFE does not help, or can actually increase friction in piano actions. I'm curious to hear more about others' experience, especially any measurements, using Sailkote.

TIA.

So, first of all, what exactly is "Sailkote"? Is it not just another of their PTFE-based lubricant/mold-release products?

Here's the MSDS, I don't see teflon in there, but I'm not good at deciphering these things: https://www.harken.com/uploadedFile...2_Sailkote-Domestic-Aerosol_MSDS_Eng.PDF

As for mold release, I think that's an additive to the original Sailkote. I don't think the original Sailkote has any anti-mold properties.

What would also be nice to know is if this is the secret, super-slick stuff Chris is using. Chris, just post a smiley if it is. We won't tell anyone

Sailkote has no smell that I noticed. Of course, it's a spray, so there's a propellant, but once that evaporates there is no smell. I'm not sure what is in it, but I wouldn't be surprised if Teflon was one of constituents. I did careful friction tests, comparing Sailkote, McLube 444, and Teflon powder applied to both felts and escaine knuckles. Sailkote provided the lowest friction of all 3. Teflon powder actually increased the friction when applied to brand new knuckles, but on the positive side, it seems to eliminate or greatly reduce stiction (https://en.wikipedia.org/wiki/Stiction). Knuckles with Teflon powder feel greasy rather than slick.

Sailkote is not a mold-release product. It was designed to be applied to sailboat sails to reduce friction, and so it is intended to be applied to cloth or cloth-like surfaces. I have sprayed it directly on knuckles, while using some newspaper to keep it off adjacent parts (there's always overspray). Once dry, you wouldn't know it was there except for the reduction in friction.

It's correct that brass capstans aren't so bad, but UHMW capstans would be slipperier, and you wouldn't have a situation where some anti-friction coatings would wear off.

Like many plastics, UHMW can creep, but I think it would only be noticeable in high-load applications. I have designed in UHMW PE in other (nonpiano) applications, and it's quite a remarkable material.

"mold release" is a term for material applied to the interior of molds for plastic or other materials so that after the material hardens it comes out of the mold more easily -- rather than sticking to the inner surface of the mold. McLube 1725 (and, I believe 444) was not invented for lubrication but as a mold release agent.

This is helpful information. Thanks for the effort in testing it and also thanks for sharing it.


But, the hard-anodized aluminum capstans developed by Stanwood and now mass-produced by WN&G are superior to brass both in friction and mass. How would UHMW PE compare?

Okay, I'm not an RPT, but for all the real technicians on this thread let me give a detailed plug for WS2 based on my own experience:

On my Kawai CA95, the felt pads were getting very stuck to the brass capstans. I measured static downweight at over 90 grams. Since I like playing rather loud repertoire, I managed to knock a few of the felt pads off, and put them back on with superglue, which hardened the felt, creating squeaks. A generous dose of WS2 powder cured all problems, now it plays better than my friend's brand new CA68 and the other Kawai Grand Feel 2 actions in the store.

On my Steinway A2, I applied it to the knuckles and front key pins after Larry Buck had cleaned them up a bit. A tiny amount immediately dropped the friction under sideloading.

On my brand new Phoenix C212 with a Laukhuff keyboard, the key pins had noticeable friction when sideloaded, everything was brand new and perfectly clean and polished. I rubbed all the pins with a Q-tip with isopropanol dipped in WS2 powder, and now all the keys slide like butter even if I'm forcefully pushing them to the side. I put it on the knuckles too, and am monitoring wear.

One of the popular Protek lubricants is basically just MoS2, and WS2 is a similar compound that's more expensive and better in every metric.

That's interesting. Can I ask, what is WS2? And what is MoS2?

WS2 and MoS2 are solids with dry lubricating properties.

Tungsten diSulfide and Molybdenum diSulfide

Trigalg, do you use WS2 in powder or spray form? I read the spray really smells (don't know why everything I read says these lubricants smell funny). Did you find that to be the case?

Roy123, i share your curiousity about UHMW Polyethlylene. Not only is it highly lubricious, but it is incredibly strong. It's tensile strength exceeds that of Carbon fiber, yet it is so light that it floats on water. It is also very good at vibration damping and absorbing impact energy.

Regarding your musings about plastic bearings and the piano industry, it has already been done for hammer shanks and flanges by Igus and Phoenix Pianos in England: https://press.igus.com/2019/07/31/piano-builder-strikes-new-tune-with-help-from-igus/

In January I found out about these 3D printed shanks and flanges and shared several emails with James Bacon at Phoenix Pianos, he was one of the developers. They had finished the prototype but were not quite at the point of going to market then. That may have changed since then.

It is an interesting development to be sure.

Thank you! Silly me!

Powder, I wasn't aware of any spray formulation. It does readily form a suspension in alcohol and I imagine many other solvents so I guess there's nothing that would stop you from making a liquid that can be sprayed. The solid should have no smell, naturally.

@WilliamTruit
Yes the D3D actions are being produced by Phoenix, but WNG has been using plastic bushings for a while so Phoenix isn't the first. I saw the D3D parts last time I visited and another customer visiting the farm said he ordered a full set for his Bosendorfer. Having accidentally broken one of my WNG hammer flange assemblies (in several places after a botched repair attempt), I can appreciate the increased strength and durability of the single-piece D3D design. He also puts the "fork" on the side with the repetition lever button so there's several times more material at the thinnest point holding it all together.

I have been using the WNG shanks (and other parts) for about 10 years, so I am quite acquainted with them. The WNG shank is a pultrusion in the fiber orientation, which means that it is quite strong along its longitudinal axis and not very strong in torsion. by contrast, James Bacon told me that the shank tube is made from a helical weave of carbon fiber, which stiffens the shank in all orientations and is generally stiffer than WNG's shank. I think it likely that the tribopolymer roller bearings represent a meaningful improvement over existing technologies.

I hope they will license the technology to make it broadly available. Phoenix does not make that many pianos.

Years ago I had an old Toyota Land Cruiser with leaf springs. Squeaking from the urethane bushings drove me nuts, and greasing them only worked for about a week. I have a lathe, so I made my own bushings out of UHMW PE rod stock. Problem solved. In the 10 years I ran with those bushings until I sold the vehicle, I never saw any sign of wear or creep, and I beat the snot out of that truck on a regular basis rock crawling.

UHMW is definitely more lubricious than hard anodizing, but it's possible there are other parameters of the hard-anodized capstans that would be superior to UHMW

Would you tell us what retail source you used to obtain WS2?