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Re: Attaching key corks

Author: Chris P
Date: 2021-02-01 12:40

Contact adhesive is best.

From what I've seen going by working on a recent Recital, Selmer still uses shellac on their clarinet key corks and I'm pretty certain there are still oboe makers that use it too. It may have been the best option before modern adhesives were found to be more advantageous, but it's not the best option unless you want to stick with tradition.

There are three basic ways of using shellac to stick key corks on - either use liquid shellac (made from flakes or ground shellac dissolved in alcohol) and apply it with a brush to the corks or the undersides of the keys and then stick the cork on and wait for an age and a half for it to dry. Another is to prep all the key corks by coating one side with liquid shellac and leaving it to dry, then heat the key up and stick the cork onto it and then trim them once the key has cooled down. And another way is to heat the key up, melt some stick or flake shellac to the underside and stick the cork on whilst the shellac is still molten, then wait for it to cool down before trimming the corks up.

Whereas with contact adhesive, the best method is to make sure the underside of the key is clean and degreased, then coat that surface and also one side of the cork with a thin even layer of adhesive, leave it to become tacky and then stick both glued surfaces together, give them a squeeze to make sure there aren't any air pockets and then trim the corks up as soon as that's done.

Superglue can be used in an emergency, but it does require the key to be thoroughly degreased otherwise it won't bond, but use too much superglue and it can run or drip and stick onto places you don't want it to. Superglue has plenty of applications in clarinet repair - mostly on wooden clarinets, but not for key corks unless there's a dire need and that's the only form of adhesive you have to hand. It can be removed from wood or metal with acetone, but don't use acetone on plastic clarinets as being a solvent it can dissolve ABS and various other plastics.

And when it comes to tenon corks, contact adhesive is also best for them provided the cork slot is nice and flat (and also well cleaned and degreased) as contact adhesive is best used between two close fitting surfaces instead of deeply grooved tenon slots as that provides very little contact area between the cork and the tenon slot as the peaks of the grooves are the only areas of contact with the underside of the cork. Maximise the contact area by machining the grooves smooth and you'll get a far more successful bond. In the olden days when shellac was used, that needed the grooves to provide more surface area for better adhesion of the shellac and the cork sat on the flat layer formed when the shellac filled in the grooves - the shellac was applied molten and the cork was stuck on using a hot knife to melt the surface layer and it was a case of working fast to make the cork stick while the shellac was still molten. Or if liquid shellac was used, the cork strip was wrapped up with string once fitted to keep it in place and put aside while the shellac dried over the course of the next millennium before being able to sand the cork to the required size and shape. If you have plenty of time on your hands and want to take the slow route, then that method is ideal. If you prefer instant workability, then contact adhesive is perfect.

Shellac still has its place when it comes to installing skin, leather and cork pads (synthetic pads are best installed using hot glue as that's sticky at a much lower temperature), but contact adhesive is the best all round for key corks and tenon corks once all the necessary prep has been done.

Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.

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Attaching key corks new

ibabcock

2021-02-01 03:41