Detecting bellows leaks?

[fred v]

What is a good way to find just where the leak is? I can push on the bellows and can detect an air flow but can't find just where it's coming from.

Fred

[David Barnert]

Hold it under water, squeeze it, and see where the air bubbles emerge.

 

[ Don’t! ]  

[Theo]

Working out exactly where bellows leaks are is one of the most tricky aspects of concertina repair. I don’t think there is one foolproof method that will work in all circumstances.  
Feeling a jet of air against your face s a good start. 
listening with the concertina close to your ear can help

placing a very bright light inside the bellows and observing in a subdued room light will sometimes reveal holes

a light dusting of powdered talc over suspect areas can sometimes narrow down the location.

I’m sure there are others but those are the main methods I use.  You have to be a detective!

[fred v]

1 hour ago, Theo said:

Working out exactly where bellows leaks are is one of the most tricky aspects of concertina repair. I don’t think there is one foolproof method that will work in all circumstances.  
Feeling a jet of air against your face s a good start. 
listening with the concertina close to your ear can help

placing a very bright light inside the bellows and observing in a subdued room light will sometimes reveal holes

a light dusting of powdered talc over suspect areas can sometimes narrow down the location.

I’m sure there are others but those are the main methods I use.  You have to be a detective!

Thanks. I think the under water trick would nail it for certain!!

[David Helmore]

Hi Fred

 

I use a similar approach to what Theo has suggested but use fine sawdust instead… I find it works really well!!

 

Before I resort to this though I point an angle poised lamp through the bellows in a darkened room…

Edited October 13, 2022 by David Helmore

[JimR]

Or get yourself a smoke pen.

[SIMON GABRIELOW]

Why not try placing a hair near to bellows and if it moves you can then see where the air is leaking from?

Of course you will either need to use your own hair, or otherwise very carefully pull it off someone else's noggin! So good luck with that!😁😁

[alex_holden]

I stick my tongue out: not to lick the bellows, but because the tip of the tongue is quite sensitive to fine streams of air. If I think I've found it but I'm not certain, sometimes I wet a fingertip and touch the spot I suspect is leaking, while applying pressure to the bellows. If you've found it, you'll feel/see it bubbling.

 

Try pushing and pulling the bellows at various points in the bellows range. Some leaks get worse when they are almost fully open or closed.

 

If the bellows are leaking from multiple places, the smaller leaks generally aren't detectable until after you've patched the bigger ones.

[Stephen DOUGLASS]

I use a Boa Feather attached to a mic stand.

[SIMON GABRIELOW]

PUT A TINY AMOUNT OF TALC ON THE BELLOWS WITH A FINE BRUSH THEN SEE IF IT GETS BLOWN OUT -MAYBE THAT WILL WORK? BUT  DO NOT USE TOO MUCH! JUST A TEENY WEENY AMOUNT!

[d.elliott]

I find the use of an inspection light inside the bellows finds most issues, that and experience in knowing where to look. That, coupled with sensing air flow on the lip of the tongue and listening hard. a dab of soap bubbles with a soft water- colour paint brush work well to confirm things if usure.  

[fred v]

Thanks for all the ideas. Alex had the one that worked for me. Using my wet tongue. I found 3 little leaks on the outer corners or points of the hex. Looks like maybe paper was used there rather than leather. The leaks aren't bad and don't interfere with playing but It did seem to fall open faster than my other one.

[ttonon]

On 10/15/2022 at 12:05 PM, fred v said:

Using my wet tongue.

Yes, wetness helps also when you use your face, or other sensitive body parts.  The increased evaporation enhances the cool feeling.

[Chris Ghent]

Soapy water is very quick and absolutely specific as to location. 

[David Hornett]

I really think you have nailed it Chris, but before giving the instrument a bath you can use one of two methods , either Alex's above with a slight modification, lick your lips to make them moist pass them over the bellows, without touching the bellows of course, the leak will be felt on the lips as a soft cooling zephyr. You can also use a candle close to the bellows, but not too close, by its wavering it will pinpoint the leak. I have uses both methods with success, as well as shining a light inside in a dark room, but being the romantic I am the wet lips test normally suffices.