Hi all, my favoured whistle has cork sealed joins (a recess in the wood, with a strip of cork in it). One cork strip has just broken - how should I repair this?

This is probably routine for many of you, but the first time I have needed to do it. Where should I buy, and what sort of cork do I need? What sort of glue should I use?


Edit: I am in the UK , and thanks in advance for any help.....

Phill

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Phill

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How to profile & glue cork tenon:

Band Instrument Repair Procedures Handbook.PDF by David Bailey

It's actually the Numbered Page 11 in this .PDF (may be the 13th page of the downloaded .PDF due to title pages)

http://www.davidbaileymusicstudio.com/p ... ndbook.pdf

I can't point you to a specific source in the UK, but you can try online instrument repair suppliers, band instrument repair shops (woodwinds, etc.), and in some cases, scrapbooking craft supply shops. Scrapbookers seem to use a variety of papers for their designs, and strangely, I have found cork "paper" on the shelves that appears to be decent quality cork sheets (and no actual paper involved). Linoleum/flooring supplies also seem to carry cork sheets (I think as some sort of underlayment for tiles, etc.), but some is rough quality.

I am, however, in the U.S.

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Thank you kkrell, that is just the information I need.

https://www.windplus.net/supplies/cork_items.html
Is there any reason to choose rubber cork sheet over natural cork sheet?

I knew someone would know,

Tahnks

Phill

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Phill

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Thank you, thats what I will try then.

Just need to check thickness and I can order tomorrow. Can't be without my favourite low D can I?

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Phill

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Thanks, but part of the problem is that the cork is alrady detatching itself. The wood is well oiled and I am expecting the main difficulty to be getting the new cork to stick..... I do plenty of work in wood - mainly carving, so I have a feel for the limits of vigour that I can apply. Your advice is welcomed though, and I will report back if I encounter anything worth reporting.

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Phill

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I think the oil followed the original adhesion of the cork. I could likely be removed with a little turpentine, followed by a little ligter fuel - if needed. A glue like uhu would probably stick, and if not, the sheet of cork is plenty for several attempts. Worst case I can put slightly thinner cork on and bind with PTFE, or in real extremis return to maker for repair.

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Phill

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In this part of the world nothing is nearby (well plenty of moorland, sea, and sheep but no instrument repairers). Anyway I am an independent cuss, and will do my best to repair it myself.

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Phill

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You could also try wrapping in string, if the cork experiment fails to produce good results.

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DrPhill, I corked and re-corked thousands of tenons as a professional recorder maker/repairer, here are my suggestions FWIW:

1. If you haven’t purchased already, I’d suggest natural cork, not the rubber sheet or composite stuff. There are reasons virtually every top recorder maker uses natural cork and you only find the other stuff on lower price, mass produced models.

2. Make sure to measure the thickness of the cork that was on your instrument before ordering replacement cork - if what you buy is too thin you’ll be out of luck, too thick and you’ll have to spend time sanding it down. Buy a good bit more cork than you think you’ll need, both in length and width, you’ll need to trim it and it may take you several (failed) attempts to do the job right.

3. Barge Rubber Cement is the go to adhesive for cork on wood, if you can find it. Other rubber cements will do the job, but may or may not hold as well. You’ll also need solvents on hand to clean the old rubber cement off after removing the current cork, and also for cleaning off any excess adhesive when you’ve installed the new cork.

4. After completely removing the old cork, use solvent (as mentioned above) to clean the cork slot and remove all remnants of the previous adhesive - make sure to clean the sides of the cork channel as well. Let the wood completely dry before proceeding further.

5. If you have or can get some cheap pipe cleaners, I suggest applying a VERY thin coating of superglue to the cork slot and sides using the tip of a pipe cleaner. Do not inhale the fumes that will start to visibly come off the pipe cleaner as the glue dries. Supergluing the cork slot will aid with adhesion when it comes time to cement the cork into the slot.

6. Measure the cork slot width and lengtht and the transfer that to the cork sheet and cut to size using straight edge. Cutting the cork just right is not easy - too narrow and you will have gaps, too wide and the cork wind fit in the slot or it will bubble/buckle up. Remember you will need a generous overlength if you are using the overlap method.

7. You can try for the beveled/tapered fit that backhold posted photos by hand sanding the end to be tapered, but remember you will also need to sand the cork concentric after flying down the overlap. Getting the cork truly concentric with the whistle tenon can be very difficult by hand and failure to do so can cause unequal pressure inside socket leading to cracks in your headjoint. We avoided this by grinding newly mounted corks perfectly concentric on the lathe. Maybe a better option for you is to flush mount the ends of the cork. Your call.

8. When you’ve measured and cut the cork to size and it’s time to glue up, remember that the rubber cement needs to be applied to all surfaces that will touch one another: The floor AND walls of the cork slot, plus the bottom AND sides of the cork. Plus, if you use the tapered method then you also need to put cement on the top of the taper and the part of the overlapping cork that mate to that, but not so far than you have nothing to hold onto without cement on it. Don’t forget to allow the cement to dry on everything BEFORE attempting to mount the cork into the slot.

9. Once you fit the new cork into the slot all glued up, press it in tightly by hand then let it dry for 24 hrs if the fit is good. However if you aren’t happy with the fit at any point in the gluing process fix that immediately, before the cement fully cures.

Good luck, getting a really clean, perfectly fitting cork, that stays put for a long time in a wood cork slot is not as easy as it might seem.

Thank you Loren for taking the time to write that all out.

Some notes:
- I need to find my calipers to do the measuring
- Barge Rubber Cement? I dont recognise the term. A search on the web shows this to be the sort of thing that rubber soles are stuck to shoes with.... does this match your impression? Ah 'Barge' is the manufacturer. 'Rubber Cement' it is then.
- The superglue idea is an interesting one, sort of a primer?
- A butt (flush) joint may well be easier than a tapered joint. Maybe I could do a (45 degree?) slope on the butt joint so that it does not point directly down the whistle.
- How large a gap should I tolerate between the ends of the cork if I do a butt joint? I could fill any gap with glue, I guess.
- If my first attempt is less durable then I will get more 'opportunities to improve'.

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Phill

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Yes, caliper measurement would be good. Maybe transfer that to paper or cardboard to make a full length template and cut the cork from sheet on the template.

You are correct, Barge is the brand, I should have been more clear on that, sounds like some
sort of marine/boat thing otherwise, lol.

Superglue does act as a sort of primer: Evens out any uneven areas due to wood grain and gives a consistent surface for the adhesive to grip. Also helps save wear and tear on the wood underneath when it comes to remove or replace the cork next time as getting cork off sometimes involves scraping and prying. Many instruments we made and/or worked on were 30, 40 or more years and had been re-corked many times. The wear and tear can add up, so it’s worth taking some preventative steps.

Don’t cut the ends of the cork at a 45 degree angle, stick with 90 degrees/square ends. Remember rubber cement bonds instantly ( guess that’s why it’s also sometimes referred to as contact cement ) so you’ll have very little margin for error when applying the cork. This is important because it’s critical that you start applying the new cork dead even and going completely straight in the cork slot, otherwise problems will arise. Having the ends cut square is the only way you can’t really properly line up the cork and start applying it. I should have mentioned that you start by putting just one end of the cork in the slot, and then gradually/slowly/carefully work the rest of the cork in along the slot taking care to keep it even and flat in the slot the whole way. As I said, the rubber cement is unforgiving, so you do need to get it right the first time.

I should have also mentioned the following: Use a thin, light coating of rubber cement on the cork slot
and sides, a thick application works less well. Also use a thin application on the cork strip to be applied to the slot. Let the first application of cement to the cork dry, then do a second application of the adhesive, again a thin/light coat. The slot does not get a second coat. The cork adheres much better this way.

How much gap where the butt joint happens? As little as possible strive for perfection! But, don’t worry too much if you have a small gap, as long as your instrument doesn’t leak air while playing, the gap won’t be a big deal. Stuff can build up in the gap and eventually start causing the cork to lift off, and the exposed ends can grap on the socket a bit while assembling/disassembling which can also start to pull the cork off, these are the main reasons you don’t want a gap. If you get the gluing and mounting of the new cork right though, it should resist a fair amount of that stuff and still last a decent amount of time. Maybe

Last item: After the new cork is mounted and the cement has been left to fully cure overnight, you will likely need to do some sanding of the cork to get the proper fit. Grease the cork very well all around (cork grease or Vaseline) and then try gently inserting the tenon into the socket while twisting. If the socket does not have a wide metal band reinforcing the full length of the socket the it is imperative that you do not force a tight fitting cork into the sock, it will likely crack the socket! If it seems like the fit is significantly tighter than before the re-cork, stop and sand the cork down concentrically a little at a time pausing frequently to re-grease and fit test. This can be a little frustrating and time consuming but you don’t want a cracked socket or a new cork sanded down so much that you have to remove it and start over.

I should mention that its often worth sanding a little taper or bevel on the side edges before attempting the first socket tenon marriage with the new cork. Reason being that you don’t want that side edge of the cork catching on the side of the tenon, which can instantly, or over time, cause the cork
to lift off at the edge. Also, having the cork edges slightly lower than the main body of the cork can help in thenfitment fine tuning as a completely flat cork can lead you to believe it needs more sand than is actually necessary, to the point where once you sanded the whole cork down enough for the leading edge to fit without binding, you now find the entire fit is too loos. So, just take a little off at least the leading edge (the side that will be inserted into the socket first), or do both edges if you prefer, prior to making any full cork sanding adjustments to fit. Don’t take too much off the edges though or you’ll end up with a wobbly connection.

So there, super easy, really nothing at all to doing a good joint re-corking Have fun and let us know how it turns out!

P.S. Please forgive any typos or spelling errors, I would normally proof read but I’m short on time so....

Wow, lots of useful points there, thanks Loren. Maybe a Mod should make this into a sticky?

As for typos and spelling mistakes, well in this age of mobile phone keyboards, spell chequers and the lake, my 'error detecting circuits' have been recalibrated. Meaning I did not notice any. Does not mean that there were none, just that I concentrate on the information, not the presention.

The task is currently waiting for cork.... the maker, Phil Bleazey, is sending me some. What a nice man.

Phill

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Phill

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Predictive text is a bugger though, isn't it?

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You meant 'beggar' didn't you. (Mine were intentional, but you got the gist.....)

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Phill

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Loren worked for one of the best recorder makers in the world. He knows wherein he speaks.
Barge cement is terrific stuff. It's basically the rubber cement from hell.You'll find many other uses for it.
Wrapping the joint in thread isn't a bad option if the cork and Barge doesn't work for you. You'll want a thickish thread, not really string. Run the thread over a piece of beeswax before wrapping, then rub more beeswax over the wrapped joint.Make note of which way you wrapped the thread and when you assemble and disassemble the whistle, twist it apart in the way that tightens the string instead of loosening it.

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