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Mark Rosenthal

Question about reed pan gasket and reed pan support blocks in an 1880s Lachenal

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Posted (edited)

I have a Lachenal English concertina made in the mid-1880s.  The person I bought it from told me he bought it from Lark in the Morning in 1978 and there's reason to believe it was refurbished shortly before then.  There are a couple of things inside that strike me as odd.  But I'm more familiar with Wheatstone innards than with Lachenal innards.

 

Oddity #1: In every other concertina I've ever seen, the gasket on top of each chamber wall is made of chamois.  But in this instrument, the gasket is made of some sort of hard leather, with the rough side out.  However, the bellows end is lined with the usual chamois.  (See photo)

 

Oddity #2: In every other concertina I've ever seen, the reed pan support blocks are glued into the bellows frame.  However in this instrument, some of them are also held in with a screw.  (See photo)

 

I'm hoping people in this forum can tell me whether the things I'm finding odd are something Lachenal would have done when the instrument was built, or if it's more likely that it was done when it was refurbished about a century later.

 

This is not just a matter of idle curiosity.  Figuring out whether or not these things are original will guide me in coming up with a solution to a problem the instrument has.

 

Lachenal-ReedPanShowingGasketMaterial.jpg

Lachenal-BellowsFrameWithScrewedInReedPanSupportBlock.jpg

Edited by Mark Rosenthal

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These are the deeds of repairers. There is nothing intrinsically wrong with using different leather on the partitions, what matters is that is seals. And while I wouldn't do it, I have seen many instruments with a screw through a reedpan block. It works but seems unnecessary when glue would work on its own.   If at some time later you wanted to move the block only a small amount the screw would no longer work though you could plug the hole and drill again.  The one you picture is unfortunately placed: the screw, which is essentially a wedge, is being forced into a join between two pieces of wood. It has to be weaker than before the screw went in.

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That confirms what I suspected.

 

The problem is that for one or two notes, when you play that note, the reed from the adjacent chamber also sounds faintly.  I know it's not due to any part being warped, because before I agreed to buy the instrument, I opened it up and held a straight edge against the reed pan and against the bottom of the action board.  Initially I thought that just gluing a thin piece of paper under the gasket between the two chambers would solve the problem.  But when I tried that, the problem moved - i.e. the note that ciphered no longer ciphered, but the note a chamber or two away started ciphering with the note in an adjacent chamber.  When I tried to shim the gasket between the newly ciphering chambers with a thin piece of paper, the problem moved elsewhere.  I suspect that this is happening because the leather is hard.  I'm guessing that the reason chamois was traditionally used is because it's soft and a little compressible.  So when you screw the end onto the bellows, the chamois will take care of microscopic variations by compressing more in some places and less in others.

 

I've long suspected that what I'm going to have to do is replace the leather gasket with chamois.  But that brings up a number of other problems.  The leather gasket looks to me to be slightly thicker than most chamois I've seen in concertinas.  That means that I'm either going to have to move the reed pan support blocks, or somehow build up the height of the chamois by gluing something underneath it, or glue shims on top of the support blocks to slightly raise the reed pan.  And if I decide that moving the support blocks is the right solution, the screws are going to make that harder to do.  Any of these options is doable, but none of them sound like fun.

 

Is chamois available in different thicknesses?  And do you have any idea where I can buy chamois for this?

 

FWIW, the concertina has a label saying that the restoration was done by Colin Dipper. I guess in the 1970s, he was still learning.

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if you don't want to move the support blocks due to the screws holding them you might try to remove them and grind off the overmuch height

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21 minutes ago, Wolf Molkentin said:

if you don't want to move the support blocks due to the screws holding them you might try to remove them and grind off the overmuch height

The current leather gasket is thicker than any chamois I've seen. If I replace the leather with thinner chamois, compensating for that will require the support blocks to be higher than they currently are, not lower.

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2 minutes ago, Mark Rosenthal said:

The current leather gasket is thicker than any chamois I've seen. If I replace the leather with thinner chamois, compensating for that will require the support blocks to be higher than they currently are, not lower.

 

of course you have it right - but the advice would be basically the same: adding the required thickness by applying tiny shims...

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You should be able to find chamois leather (both the real sheepskin stuff and fake EVA stuff) in auto parts stores.  You will need to haunt these stores to find a decent piece.  Avoid the fake stuff.

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Auto parts stores?  Definitely not a place I'd have thought to go looking for concertina parts!  Thanks for the suggestion.

 

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Next question: What sort of glue would you recommend for gluing the chamois strips onto the top of the chamber walls?  I could use hot hide glue.  But I also have a PVA glue that says it's pH neutral and water soluble.

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Posted (edited)

Not a concertina repairman, but in the violin world I use Elmer's school glue for things like this. It's not particularly strong, but it's completely water soluble/removable. For something that is under a little pressure all of the time and doesn't have to be strong, it's good enough and faster than hide glue to remove.

 

Also whereas hide glue might soak in a bit and harden the leather somewhat, I don't think the school glue will do that. I wouldn't use a PVA glue--too hard to get off, too strong for the job.

Edited by mdarnton

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I would use fish glue, not a PVA glue which is only water-soluble before it is fully cured, even the kids version of it from Elmers.

 

Hot hide glue would be OK too, if you already have pot mixed and ready to apply.

 

You can get fish glue from Lee Valley - along with all sorts of interesting woody things. 

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I now (at Dave Elliott's suggestion) use gum arabic for gluing chamois leather. I have in the past used hide glue (I think that's what the vintage makers used), but I find that it's messier, more prone to soaking in and hardening the gasket, and harder to remove.

I cut the chamois into strips using an Olfa rotary cutter on a self healing cutting mat.

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Posted (edited)
On 7/13/2018 at 1:42 AM, alex_holden said:

I now (at Dave Elliott's suggestion) use gum arabic for gluing chamois leather.

 

Thanks for your suggestion.  Based on that, I went looking for gum arabic yesterday.  I found pre-mixed bottles available at local art supply stores.  (https://www.amazon.com/Winsor-Newton-Gum-Arabic-75ml/dp/B005P1RSDG)  Apparently it's used as a binder for watercolors.  The salesperson I spoke with told me it's a fairly thin, runny mixture, and he wasn't sure it would work for gluing leather to wood.

 

I also found powder that you can mix yourself, presumably to any consistency you want.  I found:

  1. a 1 oz. bottle that seems to be intended for artwork (https://www.amazon.com/JACQUARD-PRODUCTS-JAC1648-Ounce-Arabic/dp/B000WWK844),
  2. a 2 oz. bottle that seems to be intended for cooking (https://www.amazon.com/CK-Products-Gum-Arabic-Ounce/dp/B00BYIU246), and
  3. a 1 lb. package that, based on the comments, people seem to be using to make homemade hairspray, to treat gout, to enhance homemade wine, to make edible glitter, to make pigmentation for art supplies, and all sorts of other strange uses (https://www.amazon.com/Arabic-Powder-Frontier-Natural-Products/dp/B000UYIQ5M).

Do you use the pre-mixed gum arabic or the powder?

 

If you use powder, are there different varieties, some edible and some not?  Or are they all the same?

 

If you use powder, how do you know when it's the right consistency?  How much water do you mix with it?

 

Am I right in assuming that a 1 lb. package would be a multi-lifetime supply, and 1 oz. or 2 oz. would be more than enough for gluing the chamois gaskets onto the tops of the chamber walls in both reedpans?

Edited by Mark Rosenthal

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8 hours ago, Mark Rosenthal said:

Do you use the pre-mixed gum arabic or the powder?

 

If you use powder, are there different varieties, some edible and some not?  Or are they all the same?

 

If you use powder, how do you know when it's the right consistency?  How much water do you mix with it?

 

Am I right in assuming that a 1 lb. package would be a multi-lifetime supply, and 1 oz. or 2 oz. would be more than enough for gluing the chamois gaskets onto the tops of the chamber walls in both reedpans?

 

Hi Mark. I have used the food grade stuff in powder or granular form. The granules take much longer to dissolve (I suppose one could grind them with a pestle and mortar first). I'm very unscientific about quantities when mixing - I just put a small amount of water in a jar, add some gum, and occasionally stir it until it has dissolved. You can then add more water or more gum to refine the consistency. I aim for a sort of thin syrup.

 

1lb should last a long time if you keep it in an air tight container. Once mixed with water it will eventually go off; keeping it in a sealed jam jar in the fridge will greatly extend its life.

 

I apply it with a cotton bud (q-tip), brushing a thin layer onto the top of a wall, then gently laying the strip of leather onto the gum. It initially dries in a few minutes, but the bond is quite weak at first and becomes stronger over the next few hours. If you make the strips extend out past the ends of the walls, you can then trim them to a consistent length with scissors after the glue has dried.

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10 hours ago, alex_holden said:

If you make the strips extend out past the ends of the walls, you can then trim them to a consistent length with scissors after the glue has dried.

 

Thanks a lot for the additional info on gum arabic.  That's a big help.

 

As for the strips extending past the ends of the walls, I was thinking of doing what I've seen in a couple of my Aeolas.  They've got a bit of chamois (maybe 1/8" + or -) that extends past the wall and sits between the chamois that lines the bellows end and the pad/action board.  That bit is skived so it doesn't take up much space.  Maybe it will make a difference, maybe not.  Worst case is that it interferes with the seal, in which case I'll just cut the ends off at the end of the chamber wall.

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1 hour ago, Mark Rosenthal said:

As for the strips extending past the ends of the walls, I was thinking of doing what I've seen in a couple of my Aeolas.  They've got a bit of chamois (maybe 1/8" + or -) that extends past the wall and sits between the chamois that lines the bellows end and the pad/action board.  That bit is skived so it doesn't take up much space.  Maybe it will make a difference, maybe not.  Worst case is that it interferes with the seal, in which case I'll just cut the ends off at the end of the chamber wall.

 

That's what I meant. It's easier to trim them all to about 3mm after gluing them on. I used to skive the ends, but I no longer think it's necessary.

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Yep Gum Arabic, I also add a few grains of wine stabiliser, or fermentation stopper (home brew types will understand) it allows the gum to hold in its jar without scum forming, for ever!

 

I also use gum for fitting valves, and the gasket around the inside of the bellows frames, as well as fixing bellows papers, indeed most non permanent tasks 

 

Dave

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