Does My Paint-Mixing Scale Have to Be Verified as a Legal Measuring Instrument And/or Do I Need Calibration Service?

We often receive the following inquiry from auto body and paint shops:

Does our paint-mixing scale have to be verified as a legal measuring instrument (legal for trade) or calibrated at regular intervals?

Regular inspection of your paint-mixing scale by calibration and, if necessary, adjustment, is recommended in any case. You can perform calibration and/or adjustment strictly as an in-house checking procedure either on your own using a Sartorius weight, for example, or have Sartorius Service take care of this for you. If you use a paint-mixing scale in an ISO-certified shop, you will need to have regular calibration performed by a calibration service provider that has been officially accredited by a national accreditation body, such as UKAS, the UK’s national accreditation body; ANAB in the USA, and DAkkS*, the German national accreditation body. Sartorius Service with its calibration laboratories officially accredited for compliance with the International Standard ISO 17025 performs calibrations that are recognized as traceable to your particular national standards.

In most countries, you are required by law to use a verified paint-mixing scale if a weight measured on this scale is directly used to calculate a price or your scale will be used in official business transactions. Therefore, it goes without saying that a verified paint-mixing scale must be calibrated at regular intervals and subsequently verified upon expiration of the valid date of initial verification. 

Sartorius provides paint-mixing scales that are already factory-verified as legal measuring instruments for your specific location of use.

*DAkkS: Deutsche Akkreditierungsstelle that is responsible for the accreditation and monitoring of all calibration laboratories in Germany; the certificates it issues are internationally recognized.

Calibration/ Adjustment of a Paint-Mixing Scale

Controlling inspection, test and measuring equipment by monitoring its accuracy is firmly established in quality management systems. EN ISO 9001– in Germany DIN EN ISO 9001 – is the most frequently applied international standard, also adopted by the European Union, and is the procedure required by most markets. In this standard, a quality manager monitors regulatory compliance with the prescribed requirements.

For paint-mixing scales, proceed as follows to ensure valid weighing results:

  1. Calibrate your paint-mixing scale at regular, defined intervals or before each use:
    Calibration determines the relationship between the value displayed and the true mass. During calibration, no intervention occurs which would change the parameters of the paint-mixing scale.
  2. If the value displayed on your paint-mixing scale deviates significantly from the true mass, have your paint-mixing scale adjusted:
    This means that your paint-mixing scale is adjusted to reduce the deviation between the displayed value and the actual mass as far as possible, but within the prescribed maximum permissible errors.
  3. Marking
    Obtain a test seal and document showing the scale’s current calibration status
    (who does what, when, how and where)

Calibration must be performed as part of regular (audit) testing, after a regular interval has expired, after a certain number of weighing applications have been carried out or whenever the external ambient conditions to which the scale is exposed (temperature, barometric pressure, moisture) change. If a significant difference between the reading and the calibration value saved in the scale is detected, adjustment is required. This should be done by an authorized service technician. The deadlines for monitoring the accuracy of a paint-mixing scale are set by the quality manager responsible at your facility.

Paint-Mixing Scales for Weights and Measures Applications (Legal for Trade)

According to the stringent German Weights and Measures Act, “verification is any test, assessment and marking of a measuring instrument performed as ordered by a government entity or imposed by a government authority, where said test, assessment and marking are associated with the granting of permission to use such a measuring instrument within the scope of its intended use and under the appropriate conditions of use for a further verification period (paraphrased excerpt from the German-language “Mess- und Eichgesetz” [MessEG], §3).

Within the European Economic Area, paint-mixing scales are subject to compulsory verification if they are used for the following applications:

1.            Determination of mass in commercial activities

2.            Measurements used to calculate a fee, customs, a payment or similar fees due and payable

3.            Measurements used to prepare an expert opinion for legal proceedings

4.            Use in the manufacture of pre-packaged products and for determination of selling prices

 Verification is also mandatory if paint-mixing scales can be operated for such purposes without requiring any special preparation. Testing of paint-mixing scales for weights and measures applications, or as legal-for-trade instruments in countries such as Canada, Mexico and the United States, is subject to legal deadlines – as a rule, 24 months, but these can differ from country to country, however.

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