Spongy Leather Discs

[Michael Reid]

I opened up another player's instrument, a 35-key Lachenal, to help with a sticking note problem. The pad in question was practically dangling from the lever arm.

 

The root of the problem, it seemed to me, was that the leather disc on the top of the pad had become a spongy mess. Fortunately, I had some leather discs, so I removed the old one and reglued everything.

 

What surprised me was the condition of all the leather discs. Several are no longer very disc-like; they have been stretched into little three-dimensional blobs. When the pads are raised, their attachment to the lever arms seems unstable.

 

Interior markings indicate that this instrument was overhauled by Dipper in 1999. I compared the condition of the pads/discs to an instrument of mine the that was overhauled by Dipper in the early 1990s and they're hugely different. My instrument's pads are still firmly attached, and the leather discs are a very pale color; on the problem instrument, the discs are orange-brown.

 

Is deterioration of the leather discs common? Is this a function of different types of leather being used for the discs? Could climate have an affect? My instruments are kept in the very dry air of Colorado, whereas this Lachenal normally resides in Ireland.

[Frank Edgley]

The purpose of the discs is to permit a certain amount of flexibility at the pad/arm connection. This helps to ensure that the pads seat flat, especially as the point of contact with the action board will vary over time due to pad compression. In spite of what some may assume, this is not an exact science. Makers usually do not have the expertise, time or money to test each new type of leather that is used as to its characteristics over time. Bellows leather is another thing, as time has already proven what works. But as to the small mounting pads, I suspect he saw a piece of leather that looked like it would do the trick as it probably had just the right amount of flex needed. It was not possible to see what would happen over time to this "new" substance. Evidently, it had shortcomings and will most likely not be used again.

[stella24]

i dunno. have never had a problem with a modern method of using only clear UHU glue as the connecting point between leather bead and card stock as top of pad sandwich. provided the pad is made up of thin quality hairsheep leather, hairside down, next a layer of 3mm foam pad and then the cardstock. have replaced many organic pad material with the foam. time will tell.

[Michael Reid]

i dunno. have never had a problem with a modern method of using only clear UHU glue as the connecting point between leather bead and card stock as top of pad sandwich. provided the pad is made up of thin quality hairsheep leather, hairside down, next a layer of 3mm foam pad and then the cardstock. have replaced many organic pad material with the foam. time will tell.

So you skip the leather discs entirely, right? That's what I understand the Button Box is doing now on its Morse line of instruments.

 

I'm not familiar with UHU ... found a web site, http://www.saunders-usa.com/uhu/, with several different glues sold under that brand name. Which one specifically are you using? I'm using 'Sobo' PVA glue, http://www.deltacrafts.com/Crafting/Glue/, which was recommended by the Button Box.

[d.elliott]

There is another purpose to the 'dots': that of providing a good glue area of leather to card, whilst strengthening the upper layer of the card (pasteboard). I do not omit the dots. Frank is right to say that dots also provide a degree of flexibility in the action system, a sort of self leveling joint.

 

I have personally had the problem of having to manage over soft, over thick dots. If I suspect a batch of dots has this problem, then I either just don't use them, or ensure that the PVA glue used flows up around the edge of the dot to soak in and stiffen it up.

 

Where this problem usually manifests itelf it is when it's combined with another situation, like short arms dragging the pad face, or a pad face snag on the pad hole aris, or perhaps the pad catches on the action box or cover side walls.

 

As to using UhU or similar contact/ cement type adhesives. I have seen a number of instruments where glues of these types are employed. After a few years the glue seems to breakdown and go almost oily. This contamination will write off the pad, the dot (if fitted) and the lever arm bead.

 

My advice: fit dots, use PVA or animal glue, and do a job that will last as long as the original pads. My supplier does not even charge for the dots he provides with the pads I buy.

 

Dave

[David Barnert]

I'm not familiar with UHU ... found a web site, http://www.saunders-usa.com/uhu/, with several different glues sold under that brand name. Which one specifically are you using?

I had never heard of UHU either, until it was mentioned in this thread, but I gather (from a quick google and Wikipedia) that it is akin to what we know in the USA as "Glue Stick," that is, a weak adhesive (like that on a post-it note) that is applied like crayon or lipstick (although it also seems to come in tubes like toothpaste).

[Theo]

I think the use of the word UHU needs as much care as the use of the adhesives.

 

UHU is a brand, there are several different adhesives sold under this brand. I'm sure the weak 'stick adhesive' is not what stella24 is using. UHU also make a clear semi-liquid product that comes in a tube, its a solvent based quick drying adhesive, and I imagine it might work quite well, though as Dave E says, there is a question mark of its long term stability.

[Dave Prebble]

I think the use of the word UHU needs as much care as the use of the adhesives.

 

UHU is a brand, there are several different adhesives sold under this brand. I'm sure the weak 'stick adhesive' is not what stella24 is using. UHU also make a clear semi-liquid product that comes in a tube, its a solvent based quick drying adhesive, and I imagine it might work quite well, though as Dave E says, there is a question mark of its long term stability.

 

I think the use of the word UHU needs as much care as the use of the adhesives.

 

UHU is a brand, there are several different adhesives sold under this brand. I'm sure the weak 'stick adhesive' is not what stella24 is using. UHU also make a clear semi-liquid product that comes in a tube, its a solvent based quick drying adhesive, and I imagine it might work quite well, though as Dave E says, there is a question mark of its long term stability.

 

Like theo, The UHU I know is a clear solvent glue - like Champagne to a glue sniffers ... or so I'm told. It tends to be 'stringy' when you apply it and beware...do not get it on a traditional shellac/french polished finish - it will cut into it in a split second.

 

As for fixing pads I will stick to the methods tried and tested for over a century and a half. I use leather pads between the the spud and the card and always attach the pads to the lever arm with a blob of hot hide glue.

 

I have tried a whole range of synthetic glues for padmaking over the years but have settled on flour paste with some gum arabic added. Getting thin leather to stick well to woollen felt without saturating either (or both) with glue, is harder than you might think.

I also tried out various synthetic foams instead of natural felt, but soon decided that the traditional product was the best. I recently found a few samples of these foam pads some 10 years old, and they are hard and brittle and the glue (I forget which type, but quite likely UHU) has softened and all but failed. I also find that foam tends in time to compress and lose the ability to re-expand.... more so than felt.

 

One other point I would make is that some of the pads that you buy today are simply too thick. If you look at original pads in vintage boxes the pads are really quite thin... especially so in many English concertinas.

Accepted, a fair degree of compression will have taken place over the years, but it is pretty clear when you try to replace them with an 'off the shelf' thicker pad that the action geometry was set up for thinner material. When such a replacement pad is fitted, it will often not allow sufficient clearance for the airflow and will interfere with the sound from that reed unless the action is modified by removal of button dampers and/or bending lever arms.

A 3mm foam along with the card and leather facing would, I suggest be too thick for optimum performance in many, if not most, vintage concertinas.

 

Regards

 

Dave

Edited March 20, 2007 by Dave Prebble

[Richard Morse]

So you skip the leather discs entirely, right? That's what I understand the Button Box is doing now on its Morse line of instruments.

Yes, we used to use dots (what we call the leather disks) but never found a good supplier of material of just the type we wanted. We couldn't come up with an ideal material for thickness/flexibility/glue compatibility/etc. that would work well with our action geometry.

 

So instead we focused on what the dot did - provided a degree of flexibility to ensure good pad/hole contact compensation for aging and playing compression/movement. And found that we could do away with the dot entirely by using a special formulation of PVC which provides the flex. Our solution may not be historical (though I think if they had such strong/flexible glue back then they wouldn't have needed dots either) but it works at least as well and should last longer than the historical solution. No delaminating dots (less parts!), no action hang-ups from over-flexibility, more padhole/pad action travel possible....

 

OTOH, there are cases where more flexibility is needed - particularly on boxes with loop pivots and sloppy action, or if someone wants the overhaul of their vintage box to be totally along vintage lines - we'll use dots.

 

-- Rich --

[Anthony Cipolone]

So instead we focused on what the dot did - provided a degree of flexibility to ensure good pad/hole contact compensation for aging and playing compression/movement. And found that we could do away with the dot entirely by using a special formulation of PVC which provides the flex. Our solution may not be historical (though I think if they had such strong/flexible glue back then they wouldn't have needed dots either) but it works at least as well and should last longer than the historical solution. No delaminating dots (less parts!), no action hang-ups from over-flexibility, more padhole/pad action travel possible....

 

When I bought my pads from your shop, Doug Creighton (who was super-duper helpful) recommended Sobo glue. I tested it out beforehand and, based on how flexible it was when dried, decided I didn't need the leather discs because it seemed flexible enough. Seems to work just fine!

 

- Anthony

[d.elliott]

There is an interesting parallel in the use of modern materials.

 

York Minster suffered fire damage a few years ago, I visited the restoration project as it was coming to an end, and asked the equivalent of the chief engineer why they were replacing the massive roof beams with Oak, as opposed to some structural steel, even stainless steel sections, perhaps clad in oak to look original. (Heathen as I was).

 

He said something to the effect that he gave his consulting engineers a specification which included that structural members should have a proven material design life of over 800 years. Oak won. I suppose that he was not too hot on taking computer predictions.

 

I suspect that Dave P may well have got on well with the chap.

 

Dave E

[Dave Prebble]

There is an interesting parallel in the use of modern materials.

 

York Minster suffered fire damage a few years ago, I visited the restoration project as it was coming to an end, and asked the equivalent of the chief engineer why they were replacing the massive roof beams with Oak, as opposed to some structural steel, even stainless steel sections, perhaps clad in oak to look original. (Heathen as I was).

 

He said something to the effect that he gave his consulting engineers a specification which included that structural members should have a proven material design life of over 800 years. Oak won. I suppose that he was not too hot on taking computer predictions.

 

I suspect that Dave P may well have got on well with the chap.

 

Dave E

 

 

 

Indeed I do approve Dave E !

 

Steel loses it's structural integrity and reaches critical failure at temperatures slightly in excess of 540 degC.... and it does not take much of a fire to generate such temperatures (Cunning so-and-so's have to cheat by fireproofing the steel with reinforced plaster and intumescent linings and the like...)

 

Large section oak timbers burn quite dramatically for a while but, as the thickness of surface charring builds up it actually insulates and protects the core for quite a significant period of time. It is this property that in fact saved the Minster from far, far more serious damage than would have been the case with steel ....... besides oak looks so 'in keeping' with the rest of the building.....

 

Them old boys certainly knew how to build 'em .... and it seems that there was a bit of a shortage of RSJs, UB's not to mention UHU and PVA glue back in those days

 

....and didn't they make a superb job of the restoration ?

 

Regards

 

Dave P

 

ps .. bet Fred Dibnah never used UHU glue either

[Michael Reid]

Have any of you ever tried Superglue (Cyanoacrylate) for a quick pad re-gluing when you couldn't spare the time for proper glue to set?

 

I've thought about trying this, and indeed added a small tube of Superglue to my concertina bag last year. Recently a pad came off at a session and I would have tried it, except that the glue and my screwdriver were in my other concertina bag.

 

I realize that I might have to replace the grommet (donut, spud), disc (dot), and pad afterwards, but in the right circumstances I thought that might be worth it.

Edited March 21, 2007 by Michael Reid

[Frank Edgley]

Not a bad idea for an emergency. But be careful. The thin Superglue is very thin and could either leak in the case and damage the case &/or concertina, or get all over when trying to do a rush job. The thick super glue is a lot more manageable. Just a suggestion.

[Dave Prebble]

Not a bad idea for an emergency. But be careful. The thin Superglue is very thin and could either leak in the case and damage the case &/or concertina, or get all over when trying to do a rush job. The thick super glue is a lot more manageable. Just a suggestion.

 

 

Hi Frank,

 

You certainly know how to give a fellow nightmares !

 

Perhaps a small blob of well used chewing gum would get him to the end of the session?

 

Regards

 

Dave P

 

(ps Michael... I believe nail varnish remover (acetone) will disolve superglue - take along a couple of pints of that in the bag too.. for emergencies )

[d.elliott]

acetone is excellent for burning holes in polished surfaces as well

 

Dave E

[Henrik Müller]

Have any of you ever tried Superglue (Cyanoacrylate) for a quick pad re-gluing when you couldn't spare the time for proper glue to set?...

I seem to recall (from somewhere) that Cyanoacrylate glue is supposed to glue surfaces which are plane or mirror images of each other (like the nose on your Aunt's favorite porcelain dog broken off) and that it is the absorbtion of the air's humudity that makes it harden (explains why gluing together fingers works so fast...).

 

So I think the only case where Super Glue can be used for a pad emergency, is - as Frank comments - if it is the (newer) type which is a little more thick, gel-like, not watery like the original.

 

/Henrik

 

Edited to add an "e"

Edited March 22, 2007 by Henrik Müller

[John Sylte]

I used a very small dab of Shoe Goo to reattach a pad on my Renelli, my first concertina. I would definitely use it again. If ol' Chuck Wheatstone had a tube, I think it'd be standard issue