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String covers for large RH swings

  • 1.  String covers for large RH swings

    Registered Piano Technician
    Posted 11-19-2015 19:53

    I was going to respond to the thread on pinless moisture meters, but it seemed off-topic enough to warrant a new discussion.

     

    Fred, I am very interested in your experience with string covers. I had thought that string covers were primarily for high-humidity environments that have issues with rust, mold, insects, etc. We have similar humidity swings as you, but we don't have a long enough humid season to cause those kinds of problems. And like you, I have found the standard DC installations in grand pianos to be inadequate. I pretty much always install an undercover when I install a system in a grand. Do you frequently install both an undercover and a string cover? If you only install one, which is more effective? Are there particular scenarios in which you would pick one over another?

    ------------------------------
    Peter Stevenson RPT
    P.S. Piano Service
    Prince George BC
    250-562-5358
    ps@pspianoservice.com
    ------------------------------


  • 2.  RE: String covers for large RH swings

    Posted 11-19-2015 20:40

    One problem when instituting a micro-climate within a piano is when you open it up, the strings react to the surroundings. By the time you get to the treble, the middle if off a little bit. That's why I ask for the piano to be uncovered and the lid opened hours before tuning, especially if there is AC going. In a church, I ask for all this and that the heat to be at service temp.

    I've come upon verticals with full DC units. Even thought it's Summer I feel a moist warmth upon first taking off the music panel ( I don't remove the bottom panel). By the time i finished with the treble in a house that had the AC going, the middle is sharp a cent or two; the cold air affected the strings.

    My pet peeve is why have a water source under the piano in peak humidity season? it's like driving with one foot on the brake and the other on the gas. I know there is a window for activation for each aspect but if the RH doesn't get below 60% why have a tank of water there??????

    I tell people to pull the tank in the Spring, clean everything, and don't refill it until November. I feel that most of these are sold for income enhancement rather than tuning stability...in an attempt for poor tuning technique.

    That should fire up a few people... :-) 

    ------------------------------
    Regards,

    Jon Page



  • 3.  RE: String covers for large RH swings

    Posted 11-19-2015 21:26

    However, I do recommend string covers to augment the dehumidification aspect. Undercovers might be best for situations where there is a draft, disturbing the air under the sounding board.

    Around here, I recommend the heat rods w/ humidistat. I'll opt for room humidification first which will make the whole living environment better  until further micro humidification might be needed.

    I advise customers on the effects of RH and Vapor Pressure and advise them to consult with HVAC people.

    ------------------------------
    Regards,

    Jon Page



  • 4.  RE: String covers for large RH swings

    Registered Piano Technician
    Posted 11-20-2015 09:30

    In my environment, I am cautious about recommending room humidification. If it comes up I, too, suggest that they talk to real HVAC people. When it is -30 or -40 outside and people try to keep their interior RH in the 40% to 50% range, we can have serious problems with condensation and mold.

    ------------------------------
    Peter Stevenson RPT
    P.S. Piano Service
    Prince George BC
    250-562-5358
    ps@pspianoservice.com



  • 5.  RE: String covers for large RH swings

    Registered Piano Technician
    Posted 11-19-2015 21:53

     I wonder why should DC units stay on in a good environment.




  • 6.  RE: String covers for large RH swings

    Posted 11-19-2015 23:55

    To maximize their effect.

    ------------------------------
    Regards,

    Jon Page



  • 7.  RE: String covers for large RH swings

    Registered Piano Technician
    Posted 11-20-2015 11:34

    Jon-If RH is already OK what is being maximized other than the electric bill? Samuel-Simply remove pads alone or also unplug?




  • 8.  RE: String covers for large RH swings

    Posted 11-20-2015 11:08

     "I feel that most of these are sold for income enhancement rather than tuning stability...in an attempt for poor tuning technique"

    pffffff...

    not sure why i'm responding to this... probably too much free time on my hand.  oh, it's my day off.

    Jon:  sure, that's why in many cases I go from two tunings per year to once per year, and this one church that had me tune their piano every other week (they use the piano for lessons as well, mostly flute), they went to 7 to 8 tunings every year (from 23 or 25).

    as for poor tuning technique:  the tuning stability would not improve by installing a DC if the technique were to be sloppy since you can knock the piano out of tune with forte blows.

    Peter

    ------------------------------
    Petrus Janssen
    Sharpsburg GA
    770-253-5083



  • 9.  RE: String covers for large RH swings

    Posted 11-20-2015 08:31
    Jon, I am on board with your analysis here. There needs to be about a 10% hysteresis built into the design. I instruct my clients to simply pull the pads in the spring, and put new pads in the fall after the heat runs all day. If it runs only in the night, it is still too early. I also advise my clients to purchase a digital humidity gauge so they know what is happening humidity wise.

    Firing might be a bit harsh. I think they want to do the right thing. It is up to us to share our opinions and real world experience. Have you sent this post, or something similar to Damp Chaser?

    Sam Powell
    Sam Powell Piano Care
    301-873-4162
    Spowell786@verizon.net
    Sampowellpianocare.com
    Thank You!

    ------Original Message------

    One problem when instituting a micro-climate within a piano is when you open it up, the strings react to the surroundings. By the time you get to the treble, the middle if off a little bit. That's why I ask for the piano to be uncovered and the lid opened hours before tuning, especially if there is AC going. In a church, I ask for all this and that the heat to be at service temp.

    I've come upon verticals with full DC units. Even thought it's Summer I feel a moist warmth upon first taking off the music panel ( I don't remove the bottom panel). By the time i finished with the treble in a house that had the AC going, the middle is sharp a cent or two; the cold air affected the strings.

    My pet peeve is why have a water source under the piano in peak humidity season? it's like driving with one foot on the brake and the other on the gas. I know there is a window for activation for each aspect but if the RH doesn't get below 60% why have a tank of water there??????

    I tell people to pull the tank in the Spring, clean everything, and don't refill it until November. I feel that most of these are sold for income enhancement rather than tuning stability...in an attempt for poor tuning technique.

    That should fire up a few people... :-) 

    ------------------------------
    Regards,

    Jon Page
    ------------------------------


  • 10.  RE: String covers for large RH swings

    Posted 11-20-2015 11:24

    Great discussion. Lots of very interesting points being made that have obviously been well thought out. We absolutely pay attention to technician input.

    Let me begin addressing some of the comments by saying that the intention of the PLSS is to help with unstable humidity problems. There is no practical way to completely stabilize the environment that any piano is in. Some environments are better that others, but none are perfect. Paul asked about why a PLSS should stay on in a good environment. If your piano is in a "good" (who gets to define?) environment, I would suggest that it doesn't need a PLSS. But what to do if the environment is only good for part of the time? One of the issues that we all have is piano owners who can't be bothered to take 2 minutes out of their busy lives every 10 days to add water when the light blinks. I am surprised that Jon can get his customers to remove the tank at the appropriate time in the spring and put it back again when needed. Clearly he is a good communicator and is able to educate his customers better than most. I'm not saying I agree with the strategy, but there is a certain logic to it. Certainly in a situation where there is one predominant RH level for an extended period of time, having only one side of the System functioning would seem to be a good plan. We are looking closely at this. (see H-6) I do agree with the statement about poor tuning technique. It's common knowledge that  a "good" tuner's tuning will hold true through any RH swing.

    As to string covers? Yup. No question they help.

    If anyone ever wants to chat with me about this, call me at 800-438-1524, and I would be more than willing to discuss ideas for updates or even future products.

    Cheers, and sorry to Jon for not getting fired up.  ;-)

    ------------------------------
    Charles Rempel
    Sales & Marketing Director
    Dampp-Chaser Corp.
    HENDERSONVILLE NC
    828-692-8271



  • 11.  RE: String covers for large RH swings

    Registered Piano Technician
    Posted 11-20-2015 11:38

    Charles, I'll tell you a good environment.  Bosendorfer 7'4", PLSS, plus room humidifier. Room 12'x10', pine paneling  (real wood). Piano hardly ever needed more than a light touch-up. Good thing too since the piano was 2.5 hour drive through Arizona desert.

    ------------------------------
    Larry Messerly, RPT
    Bringing Harmony to Homes
    www.lacrossepianotuning.com
    ljmesserly@gmail.com
    608-518-2441
    928-899-7292



  • 12.  RE: String covers for large RH swings

    Posted 11-20-2015 12:03

    Larry, I wasn't remotely implying that "good" environments don't exist, certainly they do. I was just asking what "good" is. Obviously a room where the RH never varies more than 10% is good, great even. But where do we draw the "good" line? 20%? 30%? At the end of the day a smaller number is better. The PLSS aims to make it smaller. Are there situations where the PLSS is unnecessary? Absolutely.

    ------------------------------
    Charles Rempel
    Sales & Marketing Director
    Dampp-Chaser Corp.
    HENDERSONVILLE NC
    828-692-8271



  • 13.  RE: String covers for large RH swings

    Registered Piano Technician
    Posted 11-20-2015 15:54

    Charles, I was implying that PLSS makes a good environment great!

    ------------------------------
    Larry Messerly, RPT
    Bringing Harmony to Homes
    www.lacrossepianotuning.com
    ljmesserly@gmail.com
    608-518-2441
    928-899-7292



  • 14.  RE: String covers for large RH swings

    Registered Piano Technician
    Posted 11-20-2015 15:43

    Peter,

    I don't have that much experience with string covers: customers balk at the price. But in the couple pianos where I installed one the effect seems larger than an undercover (one of them doesn't have an undercover as well, and it is actually the more stable piano). 

    My previous experience has been borne out by by participation in a beta test of a new Dampp-Chaser product, for which I signed a non-disclosure statement. I think I can probably avoid violating that agreement by being non-specific as to how it works, and simply state that the space under the soundboard is sealed, and that space is VERY tightly controlled as to RH, frighteningly well controlled as in + or - 1%. The datalogger for inside the cavity has a straight line for RH. I have only had it operating for a few months, but now that we have had the annual autumn drop in RH, I still experienced pitch fluctuations of a magnitude and type I am used to (not all that much different from what I got with heating bars and a DRY humidistat installed), so I am concluding that a lot of the pitch related instability takes place up top, probably including the bridge. Hence, I am theorizing that if I added a string cover, that might make a big difference. If I continue testing long enough, I might go ahead and do that as an experiment. 

    ------------------------------
    Fred Sturm
    University of New Mexico
    fssturm@unm.edu
    http://fredsturm.net
    http://www.artoftuning.com
    "We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda



  • 15.  RE: String covers for large RH swings

    Posted 11-20-2015 17:47

    From a retired technician I inherited quite a few customers with wool string covers (Edwards, which are not currently available).

    Some just have string covers, some have dehumidifier rods, some have full d/c systems. All of them are very pleasant to maintain, having overall pitch swings in a range of about 4 to 6 cents. I have not tried removing the string covers to see what happens! But Charlotte is not generally an extreme climate, and most of my customers have newer houses that range from about 35 to 55% relative humidity over the year. (This year has been an exception, with humidity in the low 60s in many homes.)

    My impression is that vertical climate control systems are more effective than grand systems, which supports the hypothesis that it is the bridge and pinblock that produce the greater change of pitch. Bill Clayton, one of our local technicians, drapes a plastic sheet over verticals with d/c systems, tuning in a way that does not allow the warm air in the piano to escape.

    In Hawaii I saw a local technician seal the top of a grand piano with heat shrink plastic film, the sort sold to seal windows. There was a dehumidifier system in the piano; I don't remember the configuration. He said this would maintain a stable tuning for a year.

    ------------------------------
    Ed Sutton
    ed440@me.com
    704-536-7926



  • 16.  RE: String covers for large RH swings

    Posted 11-20-2015 20:40

    I mostly offer string covers that i make from wool material purchased at a fabric store. Good quality cloth will run about $15 for a grand, I gtry to find a bolt on clearance. I place the yardage on the lid with the front edge placed over the front plate flange. I'll trim the fabric using the lid as a template. This offers enough material to drape over the struts and cover the interior fully except a little on the straight bass side. I place a few thin slats of wood to keep the strings from draping on the strings: one over the dampers, one or two diagonally across the bass/tenor/treble and one resting on the diagonals down the middle of the bass strings extending over the bass bridge. Most commercial string covers tend to drape at that low end. Not only do they keep the dust away, they keep the strings from oxidation.

    ------------------------------
    43Regards,

    Jon Page



  • 17.  RE: String covers for large RH swings

    Posted 11-20-2015 23:25

    Why are string covers made of wool?

    ------------------------------
    Ed Sutton
    ed440@me.com
    704-536-7926



  • 18.  RE: String covers for large RH swings

    Member
    Posted 11-21-2015 00:17

        String covers are made of wool because

          1. Wool absorbs moisture

           2. High quality wool covers that are custom fit and supported are very attractive in the piano

           3.They are easy to clean by just shaking out

       I have a client with a Kawai grand with a maroon woolen string cover in it which I had convinced her would help against string rust, dust and dirt and moisture issues. Because of the distance I had it drop shipped to her home and instructed her how to install it advising her to leave it in the piano or if she did remove it during play to put it back in. She moved to another house and the piano was located directly under a jacuzzi bathtub. The very first time they used the whirlpool the plumbing leaked and rained down on her piano. The water actually pooled into a puddle at the bass end of the cover. Had she not had the highly absorbant wool string cover the piano would have been history. The ONLY thing that got west was the left cheek block. No water at all on the keys, soundboard, strings, action or keybed.

          I have seen other things used as string covers such as bed blankets, comforters, sheets, tablecloths.

    not only did they look bad but I doubt any had the ability that wool had.

    ------------------------------
    James Kelly
    Pawleys Island SC
    843-325-4357



  • 19.  RE: String covers for large RH swings

    Posted 11-21-2015 06:52

    I've heard that cotton retains moisture, wool allows it to evaporate.

    ------------------------------
    Regards,

    Jon Page



  • 20.  RE: String covers for large RH swings

    Registered Piano Technician
    Posted 11-21-2015 08:20

    Not directly related, but. Yeah, let's hear it for wool. This is why I've worn wool trousers for 40 years. More comfortable than jeans or chinos, and most dirt and dust just brushes off.

    ------------------------------
    Larry Messerly, RPT
    Bringing Harmony to Homes
    www.lacrossepianotuning.com
    ljmesserly@gmail.com
    608-518-2441
    928-899-7292



  • 21.  RE: String covers for large RH swings

    Posted 11-22-2015 03:36
    From an ad in the '50's
     'In Winter, warm.
     In Summer, cool.
    There is no substitute for wool.

    Courtesy London Transport - Underground, Central Line . . . . .   Michael  UK


    ------Original Message------

    Not directly related, but. Yeah, let's hear it for wool. This is why I've worn wool trousers for 40 years. More comfortable than jeans or chinos, and most dirt and dust just brushes off.

    ------------------------------
    Larry Messerly, RPT
    Bringing Harmony to Homes
    www.lacrossepianotuning.com
    ljmesserly@gmail.com
    608-518-2441
    928-899-7292
    ------------------------------


  • 22.  RE: String covers for large RH swings

    Posted 11-22-2015 08:33

    No doubt wool makes a fine cover for warm-blooded quadrupeds living in extreme climates....

    Add some gold brocade and you have a fine string cover for your high end market.

    But what if you just want to maintain a stable humidity environment inside a grand piano?

    Is wool the only choice? Why not polyester felt or fabric? Tight woven polyester is impervious enough to serve as a shower curtain. 

    Any other materials?

    ------------------------------
    Ed Sutton
    ed440@me.com
    704-536-7926



  • 23.  RE: String covers for large RH swings

    Registered Piano Technician
    Posted 11-22-2015 08:46
    Ed:
    Wool, being absorbent, will prevent trapping moisture underneath. I've seen pianos where the cover, made of acrylic wool, did not absorb the moisture. The strings rusted underneath. This was near the coast where it was very damp. I always recommend at least 50% wool content. A few pianos that were right on the water I put MusicSorb under the cover also. This worked well. I've also seen damppchaser rods under the cover in extreme cases. Most of these installations were on pianos in extremely damp areas like Coronado Island and Point Loma which are surrounded by water.
    Paul McCloud
    San Diego



    No doubt wool makes a fine cover for warm-blooded quadrupeds living in extreme climates....

    Add some gold brocade and you have a fine string cover for your high end market.

    But what if you just want to maintain a stable humidity environment inside a grand piano?

    Is wool the only choice? Why not polyester felt or fabric? Tight woven polyester is impervious enough to serve as a shower curtain.

    Any other materials? ------------------------------
    Ed Sutton

    ------Original Message------

    No doubt wool makes a fine cover for warm-blooded quadrupeds living in extreme climates....

    Add some gold brocade and you have a fine string cover for your high end market.

    But what if you just want to maintain a stable humidity environment inside a grand piano?

    Is wool the only choice? Why not polyester felt or fabric? Tight woven polyester is impervious enough to serve as a shower curtain. 

    Any other materials?

    ------------------------------
    Ed Sutton
    ed440@me.com
    704-536-7926
    ------------------------------


  • 24.  RE: String covers for large RH swings

    Posted 11-22-2015 09:44
    <Is wool the only choice? Why not polyester felt or fabric?

    Same question regarding under-string felt. Wool is about the worse choice of a material for this location and function, regarding its tendency to wick moisture. Instead co-polymer bearing and high quality thin polyester felt. Every time I mention this to anyone I get the hairy eyeball, but, this combo works great. It has excellent lubricity and has to have less tendency to corrode the string contact.



    ------Original Message------

    No doubt wool makes a fine cover for warm-blooded quadrupeds living in extreme climates....

    Add some gold brocade and you have a fine string cover for your high end market.

    But what if you just want to maintain a stable humidity environment inside a grand piano?

    Is wool the only choice? Why not polyester felt or fabric? Tight woven polyester is impervious enough to serve as a shower curtain. 

    Any other materials?

    ------------------------------
    Ed Sutton
    ed440@me.com
    704-536-7926
    ------------------------------


  • 25.  RE: String covers for large RH swings

    Registered Piano Technician
    Posted 11-22-2015 14:41

    I'm located in the what's called the "South Bay" area of L.A.  Our weather is actually very pleasant most of the time.  I'm close enough to the ocean so I seldom get the wild swings of temperature and humidity of the inland valleys.  I don't install many of these systems here since in my experience, they do little to keep the pianos I service this area in tune any better than they would fare without one. 

    The one problem I do encounter is rust.  Some of my customers are close the ocean, or in a spot where's there's fog in the winter.  In a vertical, I'll typically install a heating rod, with a humidistat if they're not too close the ocean but without the humidifier.  In a grand I'll install only a string cover.  I don't use the fancy ones that you can order.  I've got nothing against them aside from the price--and the velcroed batons which I find a pain to deal with.  Schaff sells perfectly adequate wool fabric for string covers and I carry a bolt with me.  Lay it out on the lid, chalk the outline and cut it to fit.  Place a single baton over the bass section and tie it to the plate struts.  The fabric is stiff enough it doesn't drape onto the treble strings.  When you service the piano you can easily remove the cover and shake it for cleaning.  It's simple, inexpensive and actually quite effective. Forty years of experience has taught me that the cheap polyester "baize" that yard-good stores sell, though it looks the same, will not do the job.  The cheap stuff is transparent to humidity; all it does is keep the dust off.  (Which is probably helpful--I believe that the buildup of dust on the strings contributes to them rusting, giving the moisture something to cling to, so to speak.)  I never could understand the rationale for installing  a damp chaser under the soundboard to prevent rust on the strings of a grand, but that is often how customers tell me they were sold one.  Exactly how is that going to help, being tucked away under there?  Incidentally, I find the wool fabric useful in the shop as well.  In drawers where I store tools, drill bits, string reels--anything that is likely to rust--a piece laid on top will help with this.

     The last time I phoned Schaff to order some damp chasers, they would not sell the heating unit unless I bought the humidistat along with it.  Now I'm sure that in most cases that is a good idea, but that's not really what I wanted them for.  I explained that I have customers who live in places where it's always damp.  Apparently they don't trust me to make that decision.  I don't know if this is Schaff's idea or Dampchaser's, but with all due deference to our benevolent overlords, I suspect that this new policy is more influenced by the desire to pump up sales figures, and not solely due to a wish to correct our inappropriate use of their product.  I've never heard them complain about people selling them with false promises of how they'll keep the piano in tune forever, or cure sticky action centers, or keep grand strings looking shiny.

    ------------------------------
    I Cecil Snyder
    Torrance CA
    310-542-7108



  • 26.  RE: String covers for large RH swings

    Posted 11-22-2015 15:01
    Buy rods from Moisture King. I never have, but I see they are for sale.
    Ron N

    ------Original Message------

    I'm located in the what's called the "South Bay" area of L.A.  Our weather is actually very pleasant most of the time.  I'm close enough to the ocean so I seldom get the wild swings of temperature and humidity of the inland valleys.  I don't install many of these systems here since in my experience, they do little to keep the pianos I service this area in tune any better than they would fare without one. 

    The one problem I do encounter is rust.  Some of my customers are close the ocean, or in a spot where's there's fog in the winter.  In a vertical, I'll typically install a heating rod, with a humidistat if they're not too close the ocean but without the humidifier.  In a grand I'll install only a string cover.  I don't use the fancy ones that you can order.  I've got nothing against them aside from the price--and the velcroed batons which I find a pain to deal with.  Schaff sells perfectly adequate wool fabric for string covers and I carry a bolt with me.  Lay it out on the lid, chalk the outline and cut it to fit.  Place a single baton over the bass section and tie it to the plate struts.  The fabric is stiff enough it doesn't drape onto the treble strings.  When you service the piano you can easily remove the cover and shake it for cleaning.  It's simple, inexpensive and actually quite effective. Forty years of experience has taught me that the cheap polyester "baize" that yard-good stores sell, though it looks the same, will not do the job.  The cheap stuff is transparent to humidity; all it does is keep the dust off.  (Which is probably helpful--I believe that the buildup of dust on the strings contributes to them rusting, giving the moisture something to cling to, so to speak.)  I never could understand the rationale for installing  a damp chaser under the soundboard to prevent rust on the strings of a grand, but that is often how customers tell me they were sold one.  Exactly how is that going to help, being tucked away under there?  Incidentally, I find the wool fabric useful in the shop as well.  In drawers where I store tools, drill bits, string reels--anything that is likely to rust--a piece laid on top will help with this.

     The last time I phoned Schaff to order some damp chasers, they would not sell the heating unit unless I bought the humidistat along with it.  Now I'm sure that in most cases that is a good idea, but that's not really what I wanted them for.  I explained that I have customers who live in places where it's always damp.  Apparently they don't trust me to make that decision.  I don't know if this is Schaff's idea or Dampchaser's, but with all due deference to our benevolent overlords, I suspect that this new policy is more influenced by the desire to pump up sales figures, and not solely due to a wish to correct our inappropriate use of their product.  I've never heard them complain about people selling them with false promises of how they'll keep the piano in tune forever, or cure sticky action centers, or keep grand strings looking shiny.

    ------------------------------
    I Cecil Snyder
    Torrance CA
    310-542-7108
    ------------------------------


  • 27.  RE: String covers for large RH swings

    Registered Piano Technician
    Posted 11-22-2015 15:23

    I had an interesting debate with a client last year regarding his Dampp-chaser. He was convinced that it had a regular and high mode. I tried to explain to him that the system was either off or on, but he wasn't buying it. He had a temp sensor under the piano near the soundboard and noticed that the temperature went up to a certain level when the system first turned on, and then after a little while the temperature would jump up again to a higher level. 

    It turned out that his sensor was right above one of the dehumidifier rods - when it first turned on, he would get one reading. Eventually a layer of warm air accumulated enough to envelope the sensor causing the temp to jump up to the next level. 

    This really proved to me that the warm air creates a thick  layer under the soundboard panel. The piano, being like an inverted bell basically "fills up" with warm air. It would be interesting to put a sensor on the top side and see if there is any temperature change after the system comes on. i would bet, with the lid down, or with a string cover, some of that warm air convections up through the nose bolt holes. 

    ------------------------------
    Ryan Sowers
    Olympia WA
    360-705-4160



  • 28.  RE: String covers for large RH swings

    Posted 11-22-2015 17:12
    It's called convection. Science has suspected it's existence for some
    time now. A string cover or overall cover helps keep the warm air that
    rises up through the nose bolt holes down on the bridge where it limits
    the bridge's reaction to the humidity swings it would experience without
    the cover. So a string cover or overall cover helps the DC to stabilize
    the environment in the piano and improves tuning stability as a result.
    Ron N

    ------Original Message------

    I had an interesting debate with a client last year regarding his Dampp-chaser. He was convinced that it had a regular and high mode. I tried to explain to him that the system was either off or on, but he wasn't buying it. He had a temp sensor under the piano near the soundboard and noticed that the temperature went up to a certain level when the system first turned on, and then after a little while the temperature would jump up again to a higher level. 

    It turned out that his sensor was right above one of the dehumidifier rods - when it first turned on, he would get one reading. Eventually a layer of warm air accumulated enough to envelope the sensor causing the temp to jump up to the next level. 

    This really proved to me that the warm air creates a thick  layer under the soundboard panel. The piano, being like an inverted bell basically "fills up" with warm air. It would be interesting to put a sensor on the top side and see if there is any temperature change after the system comes on. i would bet, with the lid down, or with a string cover, some of that warm air convections up through the nose bolt holes. 

    ------------------------------
    Ryan Sowers
    Olympia WA
    360-705-4160
    ------------------------------


  • 29.  RE: String covers for large RH swings

    Posted 11-22-2015 16:41

    <Same question regarding under-string felt. Wool is about the worse choice of a material for this location and function, regardingi ts tendency to wick moisture. Instead co-polymer bearing and high quality thin polyester felt. Every time I mention this to anyone I get the hairy eyeball, but, this combo works great. It has excellent lubricity and has to have less tendency to corrode the string contact.>

    Jim- This sounds like good thinking to me!

    Similarly, graphite is hygroscopic, attracting moisture from the air, and it's use on bridge tops should be questioned.

    ------------------------------
    Ed Sutton
    ed440@me.com
    704-536-7926