Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Hammer Voicing w/Acetone

Acetone is so volatile that ratios do not last for long. Like so much of our business, it is more of an art than a science.

I still say chemicals should be a last resort after tuning, regulating, shaping, aligning, traveling, etc. Once you've got plastic in the hammers, it's in there for good. I've found that the need for chemicals is greatly reduced or (sometimes) even eliminated when the piano is put in good working order.

Plexiglass is a polymer of methyl methacrylate ( PMMA ). I like a thin dilution of plexiglass in acetone. About one piece of plexi one inch wide by three inches long in a pint of acetone. You can test it by putting a drop on the back of your hand. A very thin residue skin should be left on your hand once the acetone evaporates. It almost looks like a very thin film of glue.

I think the plexi works differently than lacquer. The plexi seems to glue the fibers together while nitrocellulose lacquer and other "solids" (sanding sealer etc) actually fill in the spaces between the fibers and also act as a glue. The plexi is easier to voice down but doesn't build up the hammer like lacquer does. Typically people add lacquer to the low shoulders of the hammer and build it up slowly. With plexi, go right to the high shoulder (10 and 2 o'clock), or closer to the strike point, and let the fuild undermind and work its way under the felt of the strike point. You can see it by watching the side of the hammer as you apply with an eye dropper. As an aside, don't use a paint brush because the acetone with dissolve the paint on the handle of the paint brush and you'll stain the hammer. The results are much faster and more stable than lacquer. I think it actually takes several days to hear the final result with lacquer and in fact maybe longer than that. The lacquer continues to harden over several weeks and the voice will change throughout that time. Humidity also changes the sound of lacquer dramatically. That doesn't really happen with plexi. It's much more immediate (15 to 30 minutes) and far more stable. Go the Home Depot and buy the softest plexiglass you can find and that's it. There are some suppliers that sell plexiglass beads. I don't think there is anything special about those beads, but if you go with that, then I think it's a teaspoon of beads in a pint of acetone. I believe Ari Isaacs uses plexiglass on his hammers.

This is why my preferred method of voicing primarily new hammers that are just too soft even after other techniques have been tried is to use an ultra light solution right on the striking surface. It does not penetrate very far. It will provide the desired firmness and can immediately be adjusted with a single needle technique if necessary. Once the string wears through the hardened area, the original felt remains uncontaminated or changed in any way. It can be reshaped and otherwise voiced normally from that point on.

The only exception to this is are the highest treble hammers which often need to be very hard. They can be more thoroughly saturated but can still be needled if necessary. These methods were taught to me by the Steinway people. Whether or not they are still in common use, they have always worked for me, so I still continue to use them. I would say however, that I don't find a need to do it very often at all.

By the same token, although off topic for this thread but in response to your comments about chemicals, the use of alcohol and/or acetone for freeing up an action with gummy, sluggish action centers (such as with verdigris or some kind of inappropriate lubrication) is a preferred first attempt method over lubrication.

Once the alcohol (which contains water) has evaporated, it leaves no residue or contaminate of any kind. The action of the water in the solution serves to swell the surrounding wood, thereby compressing the cloth bushing. When the liquids have evaporated, the action center is free because of physical pressure having been applied to the cloth bushing and the gummy or sticky substances have also been broken down. This is often called a shrinking solution and is not the same as lubrication although it can be just as effective or even more so than lubrication.

This is not to say that there is no place for lubricants such as Protek which is specifically designed to break down verdigris. A highly resistant (thoroughly stuck) action can be remedied with a combination approach. If the shrinking solution is effective, it can be topped off, so to speak, with Protek which will keep the verdigris at bay and provide for reduction of friction over a longer term with the polymers which are left behind.

These techniques, of course are for old pianos of low value and are a way of providing efficient and cost effective service to the clients who have them. They can also work for finer pianos such as early 20th Century Steinways, both grand and vertical which often have problems with verdigris. Not everyone who has one of these instruments is prepared to immediately spring for a rebuilding. These techniques can be used until such time as the client is ready for rebuilding or, as in many cases, until they pass away and the piano is sold and gets rebuilt at that time.

Also, I often use a judicious amount of lubricant in the case of a new piano which has a few sluggish keys; the kind that sag when the damper pedal is used. This indicates a very marginal degree of too much friction and should be treated accordingly. Rather than crunching the wood of the key mortise with key easing pliers, I prefer to give the key bushing a shot of "wet lube" that I get from Schaff piano supply. I may also gently give the key some side pressure with my fingers or a flange spacing tool to compress the felt only without damaging the wood of the key mortise. The combination of a physical adjustment and the introduction of the friction reducing polymers solves the immediate problem. As the key bushing cloth wears naturally, the problem generally does not recur and is therefore a permanent solution to the problem.

... and this would be a good reason to use some kind of white plastic, like keytops or ping-pong balls or whatever. That way you can se how concentrated your mix is (thanks Bill for that suggestion earlier, it has worked well for me).

As a chemist, I feel to contribute my two cents and to a large extent agree with Loren.

There are two main potential concerns of using impregnating polymers:
1) If one uses some actual material, like key-tops, plexiglass beads, etc - there will be fillers and modifiers present (pigments, dyes, antioxidants, etc) that for the most part are hardly desirable to go into the hammers.
Especially in the case of key-tops, some manufactures could try different polymers (composition, modifiers) - for instance our tuner thinks that the key-tops are made of cellulose acetate.
2) Even in the case of pure polymers, for the very same composition, their most important characteristic for mechanical properties is their molecular weight (length of the polymer chains or the number of repeating monomer units -for instance the cellulose (the main component of the wood) is made of the repeating glucose fragments). As Ralph alluded - there are softer and harder Plexiglas batches.
Polymer molecular weight will affect the viscosity of the solution (perceived "thickness" for the same mass ratios) and therefore the depth of the solution penetration into the hammers and the hardness/stickiness of the resulting impregnating material - all of which should affect the hammers strongly.

I once mentioned that brass bocce balls come in two types, one that bounces, and another that does not. The type that does not bounce is filled with rubber bands and weights, which make it work like a dead blow hammer. A piano hammer that works that way will impart more energy to the string, as long as the hammer bounces off of it fast enough to keep it from damping the energy. A harder shell will help keep it from damping so much. So voicing is the art of balancing these two concerns, imparting energy to the string, and controlling the amount of damping from the hammer blow itself.

Wouldn't want the guy to miss:

http://www.youtube.com/watch?v=-jWnanFVp_M


No juicing or needles needed:

http://www.youtube.com/watch?v=YDPW2Z0obgk&feature=related

Yes, no needles, no lacker, no tuning, but no piano neither.

You can voice by pressing a button, yes; but even then it won't sound like a piano.

I like that voicing block the guy is using for battery voicing. I need to get/make one of those!

I like it also. I seems to firmly hold the hammer heads. I wonder if it would work on any brand of pianos. It must fit the length of hammershanks to work properly, so it must be length adjustable.

It is adjustable, he adjusts it during the voicing...watch closely. Anyone know who makes it?

Yes, indeed!

The brand is printed on the tool, but I can not get to read it!

I posted a question about where he got the tool on his youtube video page. I went to his website: http://www.uranus.dti.ne.jp/~guter/ and it's all in Japanese.

He also posts on this forum, as A=443, so you could try a private message here as well. Or he might read this

Thanks Phil, I just sent him a PM.

I expect some “rolling of the eyes” for what I am about to post. But maybe it will be of some use to someone somewhere at sometime.

Scorching the felt and then removing the scorched layer will leave the outer layer of a hammer tighter and brighten the tone. Try it on a scrap piece of hammer felt or on a project piano if you are really interested. I suspect this is how Steinway hammers were voiced up at one time. Dr. White describes the technique.

Do you mean scorching with the opened flame, like lighter?

No, with a hot iron. Dr. White describes using a chisel heated on a burner, if I remember right. I have used the back of an electric hammer iron that was very hot. The char acts like insulation. It only blackens so far down. Then when you remove the char, there is a light tan layer underneath that has shrunk. I think a small wire hand brush works well. Sandpaper can be used, too.

Jeff,

I also remember reading about this technique in White's book and I've tried it a couple of times and it does work. Wouldn't be something to try in a client's house though!

The last piano I tried it on was a 20 year old Yamaha P22 school piano that had really harsh tone so I got really aggressive with the needles and the tone ended up overly soft so I thought I try the iron. Light ironing didn't do enough so I went ahead and scorched the felt. The results were pretty good. The shoulders seemed to retain much of the flexibility but the tone came up substantially and there was a nice crisp (crispy ) attack but without the harshness.

School pianos are good pianos to experiment on!