What is the difference between an analytical balance and a precision balance?

An analytical balance provides readability of 0.1 mg or better, while a precision balance typically reads to 0.001 g or 0.01 g. Analytical balances include draft shields and are designed for highly sensitive measurements. Precision balances handle larger samples and are less affected by environmental conditions.

What readability do I need for my lab application?

You need a readability that is at least one-tenth of your smallest sample weight or required measurement increment. For example, measuring 100 mg samples may require 0.01 mg readability, while gram-level work may only need 0.01 g. Selecting higher readability than necessary increases cost without improving results.

Do lab balances need to be calibrated?

Yes, all lab balances require regular calibration to maintain accuracy. Calibration ensures measurements remain traceable to certified standards. Internal calibration simplifies this process by automating adjustments, while external calibration requires manual verification with certified weights. In regulated environments, calibration records must be documented and retained.

What is the difference between readability and repeatability?

Readability is the smallest increment of weight a balance will display. Repeatability is the degree of agreement between multiple measurements of the same mass, on the same balance, under the same conditions.

What is the best way to clean my balance to ensure accurate readings?

Inspect and clean before each use. A flannel cloth or soft brush works well for dusting and light cleaning. Use a non-abrasive cleaner for light spills, and a dry flannel cloth for glass parts. Set a regular maintenance schedule for deep cleaning to ensure optimal performance and instrument longevity.

Can vibration affect the accuracy of my balance?

Yes — even slight vibration from a heavy footstep can affect accuracy. Place the balance on a sturdy benchtop away from high-traffic areas such as hallways, elevators, stairways, and doors. If that placement is not possible, an anti-vibration table should be considered.

Encore Tech Challenge: Using Sieves to Identify Mesh Range

Pam runs Powder Inc’s Research and Development lab. She is looking for sieves to help identify the mesh range of their activated charcoal powder, as well as quantify (for quality reasons) the percentage that falls into each mesh size. They expect a range of 200 to 400 mesh. What would you suggest?

Sieves

A: The Cole-Parmer^® sieve shaker for 3″ sieves and sieves

B: Standard 12″ testing sieves in a range from 200 to 400 mesh

C: Standard 8″ testing sieves in a range from 200 to 400 mesh

D: A Ro-Tap^® sieve shaker with sieves

Answers:

A: The Cole-Parmer^® sieve shaker for 3″ sieves and sieves. Correct! This economical shaker and selected sieves will separate into five mesh ranges. Plus, the uniform motion and digital timer provide reproducible results as compared to hand-sieving.

B. Standard 12″ Testing Sieves in a range from 200 to 400 mesh. Incorrect. Other more reproducible options are available.

C: Standard 8″ Testing Sieves in a range from 200 to 400 mesh. Incorrect. Other more reproducible options are available.

D: A Ro-Tap® sieve shaker with sieves. Incorrect. Although this would provide reproducible results in the mesh range required, there is a more economical option for Pam’s R&D testing needs.

Encore Tech Challenge: Using Sieves to Identify Mesh Range

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