There are two Essential Factors in Bellows efficiency;
Airtightness and Mechanical issues.
It is imperative that bellows are airtight.
If it is suspected that air is leaking then a simple test must be carried out to check.
Plug the exit with a finger or cork and squeeze the bellows as would be done when playing.
If the bellows deflate at all then they are not airtight.
Potentially, there are four problem areas.
- The surface of the leather.
Diagnosis – water spread on the surface of the leather will produce bubbles when the bellows are put under pressure.
Treatment may or may not be successful depending on the state of the leather.
Prepare a mixture of 75% Neetsfoot oil and 25% melted beeswax.
Remove the housing of the non-return valve and pour 50 ml of the oil/beeswax mixture into the bellows. Work the mixture into the leather. More oil and wax can be used if it doesn’t appear to be enough.
Drain any excess.
If the oily mixture leaks through the surface of leather then it is unlikely that the treatment will form a long-term solution to the problem, as the leather is no longer fit for purpose.
In my experience there is no point in persisting and new bellows should be purchased.
- The Inlet Valve.
Using the same airtightness test; if air can be felt escaping from the inlet valve then the problem must be investigated.
It must be determined whether the leaking air is coming from the joint of the valve housing with the bellows or the valve itself.
If it is the joint then this can be tightened by roughing up the hemp or adding a few layers of cotton thread.
The most common problem however is that the valve is not seated correctly. In particular if the arm of the valve is too long then there will be gap between the leather valve and the flat of the wood on which the valve closes. By holding the valve up to a light source this gap can be easily seen. The solution is to re tie the valve, ensuring that the valve fits flat on to the wood leaving no gaps.
In many cases the valve can successfully be retied but it may be necessary to replace it.
- The Outlet Pipe and the join to the blow pipe.
Again, using the same diagnostic test as described it should be able to isolate the source of the leaking air and appropriate action should be used to fix the leak.
- The stitch line where the leather is stitched into the wood. It may be possible to solve the problem of leaking air from this area by rubbing beeswax into the stitch line.
B. Mechanical Issues.
- Length of the blow pipe.
It is very important to adjust the blowpipe to be the correct length so that the arm presses on the bellows towards the back of the paddles.
If the blowpipe is too long, the bellows are pushed round so that the right elbow will be in contact and pushing the bellows too close to the front and thus producing a mechanical inefficiency. In this case, the arm may also interfere with the inlet valve.
If the blowpipe is too short, there may be a repeated problem with the blowpipe joint popping out.
2.The leather cheeks may not hold their shape and become concave when the bellows are filling with air. This produces a huge efficiency problem. In this case the leather will have lost sufficient tensile strength to retain its convex shape and it is unlikely that the problem can be fixed. New bellows should be purchased.
The bag must be airtight for the pipes to function to their full potential.
If it is suspected that the bag is loosing air, remove the bag cover, take the drones and chanter out of their stocks, plug the stocks and fill the bag with air. The bag should remain taught and full.
If it deflates then it must be determined if the leak is coming through the surface of the skin, through the seem or in fact as a result of a faulty or ill fitting valve.
Valve. Air can be felt and or heard escaping from the blow pipe. The valve should either be re-set or replaced.
Seem or Skin. Smear some water on to seem and over the surface of the leather and bubbles will be seen escaping where the bag is leaking.
It may well be that if the air is leaking from the seem, that the bag needs replaced but before renewing the bag, a repair can be attempted by pressing melted bees wax into the stitch line. This may effect a cure even if it is temporary.
If the air is escaping from the surface of the bag then it will have to be seasoned with neatsfoot oil by pouring 100 milliliters of oil into the bag via the blow pipe stock and rubbing this in to every part of the internal surface of the bag.
The bag should be hung up after this procedure in a way that ensures all excess oil drains from the bag.
Re-assemble the pipes after they have been seasoned and take care to wipe any oil from the inside of the stocks thus ensuring that oil does not get on to the reeds or the inlet valve of the blow pipe.
Humidification of The Pipes.
The most important and common cause of problems with cane reeds is a lack of humidity. When the Relative Humidity (R.H.) drops below 40% there is a high chance that the reed will give trouble.
It is usual that in cold climates in winter that the R.H will be too low. Hot dry climates will also be problematic, e.g. in certain areas of The South of France or Southern California in summer.
A few Suggestions which will help.
1. Always keep your pipes in the most humid room in the house. The humidity of the room can be increased with the use of an electric room humidifier.
2. Keep a violin humidifier in the pipe case.
3. Blow a couple of breaths into the bag via the blow pipe each day.
4. A dampened tampon can be inserted into the bag via the blow pipe and this can be kept moist at regular intervals or when required.
5. With the use of a small electric humidifier a moist stream of air can be pointed at the inlet valve of the bellows when the pipes are being played.
One or all or a combination of these measures should ensure your pipes keep playing through dry conditions.