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Hohner International (Bastari) D20/40/8 repairs


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I just received a very old, pre Chinese, Hohner International (Bastari) D20/40/8. It plays very nice and the sound is very good.

It has a red Mother of toilet seat finish, which is pealing off. Some places the pearloid cover is very buckled and I do not think it can be glued back. Can anybody please advise how I can repair it? Should I rather remove all the pearloid plastic and clean and sand the wood and then stain and varnish the wood?

Any help will be appreciated.

Thank you.

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The wood underneath won't be much to look at. I'm currently working on a similar instrument with the same issue, and I've opted to apply a cherry veneer. The labor is more than the value of the instrument, but it has sentimental value for a friend, so I figure it's worth it. If it were my own instrument, I might be tempted to just apply contact paper with a fun pattern instead.

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I have loads of genuine veneer here at my home from when I made venered boxes a while back; including Sapelle mahogany, a glorious Satin wood, and maple..  High quality stuff. I imagine it would not be that difficult to apply over the old surface; (once grotty stuff removed), and would varnish or polish up very nicely.

Do not know if of much help to you

But worth considering?

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Re-veneering might be your elegant solution, but if you want to repair (as I think you asked?) the pearloid is probably cellulose nitrate or cellulose acetate, early plastics.  Acetone is probably a solvent, and can be used to dissolve chunks of new stuff to patch the old, as I recall.  But beware of fumes, flames, and potential skin reaction.  Personally, I am less affected by those chems than by epoxy, urethane, or satinwood.  I get a horrible pustulent rash from sanding satinwood, or lacewood, or zebra.  

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Thank you for your help, I appreciate it.

Theo, I have contacted that supplier, I hope they can help.

On Aliexpress they also advertise veneer, but international shipping from them to me is a nightmare. It takes over two months and you are lucky to get it. Our postal services is a real nightmare.

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I have celluloid sheet of you want to try that, but applying wood veneer is almost certainly easier.

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It would be possibly quite difficult to post you veneer from over here in UK .. maybe expensive postage; but could in future ? All good veneer mahogany, satin wood,  [smaller billets would have been easier to send].. but if South Africa not certain.

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Thank you Simon, I have found veneer. The company gives away free A4 size samples and they sent me enough to do ten concertinas.

Now, I have never worked with veneer. Can anybody please give some instructions how to do it the correct way? How do I get the holes for the buttons and sound holes? Should I first mark the holes with a pencil and then punch it out, and then glue the sheet to the ends, and when it is dry, finish it off with a dremel? Will PVA glue be ok?

Thank you for your help

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Multiple ways to go with this. Typically either contact cement or hot hide glue would be used, but there are other options. The glue you choose will determine the process and tools that you use. There are plenty of good tutorials on YouTube. No matter what, the surface needs to be flat. You may find that the corners of the ends are slightly rounded over, and it will take a lot of (careful!) sanding to make everything even.

 

My approach to the holes is to ignore them while veneering, then drill through the veneer with a sharp brad point bit that's close to the final size, using the original hole on the back as a guide. Make sure you have a sacrificial piece firmly secured to the face to prevent tearout. Then follow up with small files or a dremel to get all the way back to the original hole size. Again, be careful! It's very easy to take a hole out of round this way.

 

Plan out the order you're going to veneer the faces in. For example, you should do the hexagonal faces of the ends last, so that you don't see the edge of the veneer on the sides.

 

Do some veneering on practice pieces before you attempt it on your concertina. You want to be confident that it will go right before you have to get it right.

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I recommend not using any glue that has water in it for veneering the end boards. If you do there's a high risk of them warping when the glue dries. Polyurethane glue, contact adhesive, or epoxy resin are some examples of glue that don't contain water.

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I agree with Steve about putting the veneer on first, then transferring the holes through from the back, but I would probably go about it in a different order:

1. Carefully sharpen the brad point bit so it cuts cleanly, paying particular attention to the outer points that score the wood.

2. Make a guide that fits in the existing button hole with a small hole in the centre, e.g. 1.5mm diameter. Easy to make if you have a lathe but not impossible to do by hand.

3. Use the guide to drill pilot holes through the veneer from the back, centred on the old button holes.

4. Turn the board over and use the pilot holes to guide the brad point bit while you drill through the veneer from the face. Put the drill press on top speed and lower the quill very slowly.

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Another queston please: when I glue the veneer to the six edges of the hexagon, should I cut six pieces and glue them seperately, or cut one long strip and bend it over the corners?

Thank you 

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39 minutes ago, Fanie said:

Another queston please: when I glue the veneer to the six edges of the hexagon, should I cut six pieces and glue them seperately, or cut one long strip and bend it over the corners?

Thank you 

 

You won't be able to bend a strip around the corners without breaking it. I cut six pieces that are slightly larger than the sides, and glue three of them on alternate sides. After the glue dries I trim back the veneer flush with the box, then glue the other three sides on. After the glue dries, I trim them flush with the box again.

 

A useful tool to have is a sheet of 80 grit sandpaper glued to a flat surface, e.g. a sheet of glass. You can rub parts on it (e.g. the action box sides) to flatten them.

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