CLEANING OF WEIGHTS OF DIFFERENT CLASS AS PER INTERNATIONAL ORGANIZATION OF LEGAL METROLOGY
- It is important to clean weights before any measurements are made because the cleaning process may change the mass of the weight.
- Cleaning should not remove any significant amounts of weight material. Weights should be handled and stored in such a way that they stay clean.
- Before calibration, dust and any foreign particles shall be removed.
- Care must be taken not to change the surface properties of the weight (i.e. by scratching the weight).
- If a weight contains significant amounts of dirt that cannot be removed by the methods cited above, the weight or some part of it can be washed with clean alcohol, distilled water or other solvents.
- Weights with internal cavities should normally not be immersed in the solvent to avoid the possibility that the fluid will penetrate the opening.
- If there is a need to monitor the stability of a weight in use, the mass of the weight should, if possible, be determined before cleaning.
- After weights are cleaned with solvents they must be stabilized for the times given in Table below.
| Weight class | E1 | E1 | F1 | F2 to M3 |
| After cleaning with alcohol | 7–10 days | 3–6 days | 1–2 days | 1 hour |
| After cleaning with distilled water | 4–6 days | 2-3 days | 1 day | 1 hour |