Cleaning weights should be a standard practice prior to when your weights are due for calibration. Proper cleaning removes debris, rust, corrosion, and any other extraneous material from the weight that could potentially throw the weight out of tolerance. Proper cleaning also extends the life of the weight, especially cast iron standards. Cast iron is more susceptible to rust and corrosion. If the beginnings of rust and corrosion are removed on a regular basis, it slows down the breakdown of the material. On a cost basis, cleaning your standards prior to calibration reduces the amount of time the metrologist has to spend with your weights equaling less overall cost. If your weights come into the metrology lab dirty, rusty, or full of water, we reserve the right to charge additional costs to repair, clean, and paint weights to restore it to its original condition as much as possible. If the weight is not repairable, we also reserve the right to condemn the weight from further use.

For proper cleaning recommendations of your standards, refer to Standard Conditions/Cleaning.


Please refer to Standard Conditions/Cleaning. If you have additional questions, please contact us.


Questions about the price of gas, being over/under changed at the gas pump, gas quality, complaints, etc. please refer to the Oil and Petroleum Section (part of the Colorado Department of Labor and Employment) at 303-318-8507.


Upon requesting a calibration for your standards, a metrologist will give you an ESTIMATE of what the turnaround time will be for your standards. If the original turnaround time quoted changes, we will contact you as soon as possible to notify you of the change and may request additional information from you. Average turnaround runs from 1 day to 2 weeks, depending on the below criteria:


  • Current Lab workload. If we are busy with other customers who have made prior appointments, we may not accept your request
  • Precision Standards take longer for calibration due to longer equilibration times in the lab.
    Volume standards can take a several days to calibrate, depending on size, number of standards, etc.
    Submitting a large number of weights at one time can take longer in order to complete the request.
  • If your standards need to be cleaned and/ or repaired can extend the amount of time in the lab. Please see Standard Condition/Cleaning.
  • If the standards are out of tolerance and need to be adjusted.
  • Missing pieces to the standards. This applies to but it is not limited to weight carts and dead weight testers.

Uncertainty is a parameter, associated with the result of a measurement that defines the range of the values that could reasonably be attributed to the measured quantity. When uncertainty is evaluated and reported in a specified way it indicates the level of confidence that the value actually lies within the range defined by the uncertainty interval.


Traceability is the property of the result of a measurement of the value of a standard whereby it can be related to stated references, usually national or international standards, through an unbroken chain of comparisons all having stated uncertainties.

This chain of comparisons, calibrations, tests, and other terms that imply a measurement involves increasing levels of accuracy for each measurement in the hierarchy reaching or traceable to the highest accuracy level or measurement origin. This measurement origin is normally standards and procedures maintained at the National Institute of Standards and Technology (NIST).


 If you are a scale or service company:



  • You are required to have an adequate amount of weight to properly test/repair/put in service scales for your customers. These standards are required to be calibrated by an accredited metrology lab on an annual basis. We issue a certificate with a one year expiration date. These standards MUST be submitted on or before the one year expiration date.
  • We accept other accredited metrology labs to complete this work for you. For a list of accredited labs, please refer to the Metrology Lab Contact webpage. To be considered "accredited" the lab MUST be at least have a CURRENT NIST certificate of traceability certificate. Please see our certificate of traceability as an example.

You are required to submit your standards (tuning forks and LIDAR) on an annual basis according to CRS 35-14-107(g). There is a one year expiration date included on your certificate. You must submit your standards on or before this date.

A reminder postcard will be sent to the current contact name we have on our database. These are usually sent out approximately one month prior to the expiration date.

If the current contact name or address is incorrect, please fill out a new postcard request form and we will update our database.

  • We do not issue an expiration date unless you specify one to our lab to comply with your current management system requirements.
  • If you did not request a specific expiration date, we issue a generic statement Certificate expiration to be determined by owner using the procedures in the National Conference of Standards Laboratories International (NCSLI) Recommended Practice RP-1, Establishment and Adjustment of Calibration Intervals. To purchase this manual for your review, please visit the NCSLI website.
  • If you like to have a specific expiration date added to your certificate, please contact us.

To better serve our legal customers (scale companies and law enforcement agencies), we automatically provide a free "reminder postcard" service. We send out this reminder approximately 1 month prior to when the standards are due for calibration (2 months for large mass).

We also provide this service to our private and commercial companies who require their standards to be done on a timed basis according to their management system requirements on a request only basis. This is a gentle reminder to you to bring in your standards prior to the expiration. To request this service for your standards, please contact the Metrology Lab and ask for a postcard request form.


There are several reasons as to why you never received a reminder postcard:


Private or commercial companies:


  • You are not required to have an expiration date stated on your certificate. If you wish to have an expiration date issued on all of your future certificates, contact us. Please refer to your own management system requirements for calibration intervals for your standards.
  • To request a postcard reminder, please contact us and ask for our postcard request form.


We do not have current contact information in our database.


  • If you have recently changed addresses, P O Boxes, or an employment change, please contact us. If our database is different, we will correct it immediately.


The postcard was sent to the wrong person


  • The person submitting the equipment may not be appropriate to receive reminder postcards.
  • The person may no longer be employed with your organization
  • You may have a designated person who is in charge of calibration intervals and we do not have it listed on our database.
  • If you need to designate an appropriate person to receive these postcards, please contact us.

The lab strongly encourages packing your standards properly to limit damage during transport to our facility. The lab is not responsible for items not shipped properly. If a package arrives in poor packaging, we try to repack it properly to limit the amount of damage leaving our facility. You may be charged accordingly if extensive repacking is required. Please refer to Shipping items for specific information.

  • We require all large mass (50 lb and larger) to be delivered on Fridays only unless pre-approved by a metrologist.
  • All deliveries must be on an open-bed truck or a truck with a lift gate. We have an overhead hoist available.
  • Truck length is limited to 45 feet (including cab) due to residential street restrictions.
  • For more information, refer to Shipping items.
  • Any deviation from the above requirements, the delivery will be refused and sent back to the customer.

There are several reasons why we cannot calibrate weights on a same day basis.


  • All weights must acclimate to our laboratory environmental conditions before calibrating.
    • Precision weights must be placed next to the balances and working standards prior to calibration at least 1 week for complete stabilization and accurate calibrations.
    • Large mass MUST sit at least overnight to limit the amount of sweating and allow the weight to stabilize to the laboratory's environmental conditions. This is especially true during the winter months. See "sweating " on weights below
  • Due to the active work load and customers who are already on the schedule for calibrations, we must take care of those appointments first.
  • We do not perform "rush calibrations" for any of our customers. We base our daily work load on appointments made on a first come, first serve policy.
  • The only exceptions to the "no same day calibrations" are law enforcement walk-ins on Wednesdays. Any other day of the week, we cannot guarantee same day turnaround.

Weights that are brought into the laboratory form a thin layer of condensation on the surface. In other words, they "sweat". This is especially true during the colder months (cold outside into a warm and humid laboratory.) This layer of water adds enough weight to the standard that can throw the weight out of tolerance, thus forcing adjustment that can be avoided if the weights were allowed to equilibrate.

To resolve this problem, we only accept large mass on Fridays to allow the weight sit over the weekend to allow the condensation to evaporate and stabilize to the laboratory's environmental conditions.