Different glassware in a laboratory are manufactured and designed for specific purposes. Each needs to be understood and maintained for use in scientific research.

Laboratory glassware are manufactured using Borosilicate and Soda-lime glass. Soda lime glass is generally used for glassware which are used for extended exposure to chemicals, categorized as Class B glassware. Class A glassware, made with Borosilicate can handle superior thermal and has greater thermal resistance, and therefore are mostly used in making chemical storage solutions like flasks.

Using Class A glassware for volumetric purpose as they can retain the chemicals for a longer working lifetime than their soda-lime equivalents. Volumetric glassware is used every day in a lab and therefore, they need constant calibration. Soda-lime glass items generally require more recalibration as they are made with borosilicate glass. ASTM 542 and ISO 4787 international standards for calibration of laboratory volumetric glassware recommend that volumetric flasks are recalibrated at the period intervals. Borosilicate glassware is recalibrated in 10 years while soda-lime in 5 years.

Volumetric glassware is manufactured and calibrated in accordance with international ISO standards. All of our volumetric glassware is marked with inscriptions in accordance with any specific standard associated with the glassware. Emphor DLAS explains various glassware categories.


Class A- Highest level of accuracy.

Class B- General purpose work calibrated to a lower level of accuracy.

Graduation marks on volumetric glass are graduated in milliliters in accordance with the ISO standard.

IN – Calibrated to contain

EX- Calibrated to deliver

Blowout- Indicates that  the last drop should be blown out

Temp °C-  All  volumetric glassware is calibrated at 20°C

Certification– All Class A glassware bears a serial number for identification and traceability. Certification confirms that the glassware is tested as per the appropriate standards and is ready to use.

Class A works certified volumetric flasks, pipettes, cylinders and burettes are inscribed with an individual serial number and calibration certificate. Certificate contains information about actual volume, uncertainty estimation for the calibration and the required tolerance for compliance. Graduated pipettes,  Measuring cylinders and burettes are calibrated at five separate points on the scale which is detailed on the certificate.

Class A volumetric flasks should also have batch certificates. The certificate should contain specific details like average volume and standard deviation for the batch.

If the volumetric glassware are used extensively, they will have to be recalibrated. Recalibration isn’t necessary, if they are new and stored for a short time. Even if they are used for a prolonged 5 years with no repeated corrosive chemical usage or with strong acids/alkalis. Age doesn’t affect accuracy. If they are subjected to moderate temperature or 121 degree C in autoclave, calibration isn’t needed.

A glassware made with soda lime glass and been used for more than 5 years or a borosilicate glass used for more than 10 years needs to be recalibrated. A glassware when subjected to more than 150 degree C, constantly used by strong acids or bases should also be subjected to recalibration.

For expert advice of glassware and their usability, you can contact engineers at Emphor DLAS. They have been providing the best glassware for their clients for quite some time.