The validity of your work is only as good as the weakest link in your method or procedure. This is why it is imperative that you regularly check the equipment that you depend upon and the balance is one such piece of equipment that should be monitored. It is very rare these days that electronic balances are used in an ideal balance room conditions, and temperature variations or ageing electronic components can often cause the balance calibration to drift, often over a short period of time. Using a calibration weight you can monitor the calibration of the balance quickly and easily and so improve the integrity of your results.

Performing a Daily Check

A balance's calibration can drift, so to have complete confidence in your weighing results it is important to carry out a daily check on you balance to ensure it is weighing accurately.
To do the daily check select the relevant weight(s) (see below) and place on balance pan and record results in a log book.  It is normal to accept some error most commonly 3 divisions.
Example : 200g x 0.1mg using a 100g check weight, allowing an error of 3 divisions
Day 1 : 100.0002mg (reference weight)
Day 2 : 100.0003mg : OK
Day 3 : 100.0004mg: OK
Day 4 : 100.0006mg : Fail, corrective action required

Corrective  action required may take the form of calling out an engineer or performing an external adjustment using a certified calibration weight

INTERNAL CALIBRATION
If your balance is equipped with internal calibration it is still important to carry out the daily check described above  in the event this feature develops a fault and adjusts the balance incorreclty.