1. Documentation and research are basic principles. Every restoration must master the importance of the instrument.
  2. Conservation first. Original material will be preserved as far as possible, damaging influence shall be minimized.
  3. A detailed plan with goals to achieve is settled with the owner before any treatment.
  4. Reversibility is striven for. If possible, glues and solvents will be used according to the original.
  5. In any case of doubt, other professionals will be consulted.