The springs are responsible for the fast and effortless movement of the keys and their accurate correspondence. We distinguish between 3 types
1. Needle-springs: They are round and are pressed into the posts. The tip is tapered to reduce the resistance and to give it more flexibility. They can easily be adjusted in strength by bending and work very fast with little resistance. The only thing you need to be aware of when you take an instrument apart is, not to break them or to stick them into your fingers.
2. Flat springs, are screwed onto the bottom of the keys. They are the preferred springs for the A and side keys of the clarinet. They are also easily to adjust but will give some more sliding resistance. In some cases, particularly with the A key, they can dig themselves either into the wood or the counter spring, which can a cause a malfunction of the A key.
Another problem can occur, when they get rusty. This can also prevent them from sliding.
If that happens, remove the corrosion and if they slide on top of another steelspring or plate, the best solution is to replace the bottom spring to one in bronze.
3. Coil-springs or spiral springs were used by the German manufacturer Kohlert and by Backun. We found them hard to adjust and difficult to work with.
They are available in several materials
1. Steel springs have a chance of getting rusty and might finally break.
2. Blue steel springs have been treated with a corrosion protective process to prevent them from breaking. Nevertheless, it might happen. Besides that are they very responsive and easily adjustable.
3. Bronze springs are like gold springs non-corrosive. Their spring elasticity is less vibrand then steel. If you have problems with corrosion, they are a perfect solution.
4. Gold: Expensive but very nice to work with, as long as the keys are not too heavy.
Since gold can´t corrode are they extremely long lasting.
5. Stainless steel or piano wire springs are cylindrical all the way. This causes less flexibility and a harder tension.
Attention: Keeping your springs always either greezed or oiled will help, to prevent them from breaking.
Alternatively, to springs are magnet systems available.