An important part of accurate weighing is regular calibration of your balances.
If you use calibration weights to perform a manual calibration, these must be handled with care to keep them accurate.
Follow our tips below to keep your weights accurate and in good condition.
Keep the weights in their original packaging where possible – this avoids weights being mixed up, and protects them from dust and other contamination.
If the original cases cannot be used, store weights under a cover such as a bell jar, resting on clean acid free tissue.
Also store the weights close to the balance where possible – this ensures they are both at the same temperature when you come to use them. If the weights are stored in a different temperature, they should be allowed to acclimatize to the same temperature as the balance before use.
Never handle calibration weights with bare hands. The oils and skin cells that can be deposited on the weight will affect the accuracy.
Once the weight is lifted handle it carefully, taking care not to let it be scratched or dragged over surfaces – including the balance pan. Place it carefully on the pan, and lift off in the same manner – scraping against the pan may cause abrasions.
Before using a weight, check it for dust, water and other contamination – these should be avoided with proper storage but still be aware.
If there is any contamination on the weight if may be carefully cleaned using a soft brush, microfibre cloth or bellows to blow dust off the surface. Never use cleaning chemicals or detergents, as these can react with the surface and form oxides, increasing the weight.
Also inspect each weight for damage before it is used – any fingerprints, marks, corrosion or other impurities will affect the weight accuracy. You may consider using a magnifying glass to check more carefully.
If a weight must be dried or cleaned with a cloth or brush, allow it to rest afterwards to let static charge dissipate.
Even with very careful care and handling, calibration weights should be recalibrated periodically to check that they are still within the acceptable tolerance range.