How to Improve Lab Weighing Results with Better Operator Technique

Whether you’re using an ultra-precise semi-micro, analytical or precision balance, the way you operate can make a difference in your results. Well-trained operators get accurate and precise weight readings while also encouraging a long life for their balance. In this blog, we’ll discuss ways you can improve your lab weighing results with better technique.

Environmental Awareness and Setup

Operator technique begins before your balance is even ready to be used: by placing it in the right location and setting it up properly.

Location

The key to choosing the best location is to pick one most isolated from environmental effects. Avoid placing your balance near a door, window or vent that could blow air towards the balance, adding force to your samples. Also avoid direct sunlight and other warm machines, as the heat can expand the plastics and metals, and even cause convection currents within draft shields.

Attempt to ground your balance in a way that won’t be impacted by vibrations. This can be difficult, as negative vibrations can be as prevalent as footsteps or traffic outside. If you can, place your balance in an area away from heavy foot-traffic. When vibrations are unavoidable, an investment like Adam’s AVT Anti-Vibration Table can help.

Finally, check the humidity levels in your lab. If the humidity level is below 40%, you’re at higher risk for generating static, which can lead to your results seeming to drift or be slower to stabilize, seemingly without reason! The most ideal humidity level is generally considered to be about 55%.

Levelling

A stable benchtop is as important as a levelled balance for receiving accurate results. Crooked or unsteady machines lead to the weight of your samples distributing unevenly across the pan. Take advantage of the built-in levelling bubble on your balance, and the adjustable feet. Before use, the air-bubble should be in the middle of the leveler, and neither your balance or the table it's on should shake or wobble.

Warm-Ups

Laboratory balances operate best when they’re allowed to warm up in their environment before you’ve used them for the first time. We usually recommend a warm-up period of around 12 hours – overnight is typically enough. This allows your balance to acclimate to room temperature and the environmental factors that remain. Once the balance is warmed up, ensure you calibrate. This will help guarantee your results are accurate and stable.

Prepping and Handling Samples

The way you prepare and handle your samples before and during weighing also has an impact on your results.

Using Appropriate Containers

There are many different types of containers that you could use to weigh your samples, like silicone, glass, plastic, tin, paper, and ceramic. It depends on what you’re weighing, of course, but in general glass and plastic have a higher potential to generate static, by rubbing against the stainless-steel weighing pan.

Avoiding Bare Hands

Avoid touching your samples with your bare hands. This can transfer sweat, oils and other particles to the sample or its container, adding a minute amount of weight. An alternative is to use tweezers or gloves. Both cotton and plastic gloves generate static, but plastic disposable gloves are at higher risk. Ensure you’re placing and removing the sample directly up and down, without dragging against the pan.

Temperature

You’ll get the best results if your samples are the same temperature as your balance. If you leave your samples beside the balance for a few hours, that can help them equalise. Of course, this is only if your samples don’t need to be hot or cold to prevent degradation.

Properly Taring and Zeroing

Taring is deceptively simple, and it’s easy to make mistakes without realizing. To operate effectively, ensure your balance is zeroed before and after every use. This will give you a clean slate to work with and ensure no ghost weights are impacting your results.

When weighing samples, always tare out the container first. This could involve having an identical empty container for taring, or always remembering to tare the container before adding the sample. It can be easy to get in a rhythm of weighing, and not to notice if the next sample has a plastic container instead of paper. If there’s a weight difference between the two, that will be added or subtracted from your results, rendering them inaccurate. Paying extra attention pays off!

Always ensure that the combined weight of the sample and its container don’t max the balance’s capacity.

Loading Technique and Placement

Where and how you load your samples is the sign of a good operator.

When loading, always place the sample in the center of the pan. This helps make sure that the weight is distributed evenly. Place it gently to avoid shock loading, which can damage the balance over time. Once the sample is on the pan, completely close the draft shield if your balance includes one. Then, wait for the reading to stabilise. You’ll see a “~” symbol, which means the readings are stable and reliable. When removing the sample, lift it straight up with tweezers or gloves, then close the draft shield again. Guarantee that the display reads zero before placing the next sample.

Recording Results

If you did everything right, but recorded the wrong result, you haven’t operated effectively! The main idea is to go slow and steady, without rushing, and to double-check your results whenever they’re truly critical.

Accessories like the AIP Impact Printer or Adam DU Data Analysis Software are extremely helpful for recording stabilized results as they happen. That way, there’s no risk of human error caused by copying down the wrong number. Adam Equipment lab balances, such as the new Polaris series, are Good Laboratory Practice compliant. Each printout will include the date, time and who was operating when the result was recorded, for effortless traceability.

Finally, always pay attention to what weighing units you’re using! It can be easy to accidentally switch from grams to ounces, and if you don’t notice, you could record the wrong ones.

Regular Maintenance

Make operation easier for your future self and improve the longevity of your balance by performing regular maintenance, which includes calibrating your lab balance regularly. If you wait too long between calibrations, you might begin to notice that your results aren’t as repeatable, or they take longer to stabilise. Invest in calibration weights to regularly verify your balance’s accuracy.

Avoid keeping samples or containers on the weighing pan when it’s not in use. This can wear out the balance’s internal mechanisms over time, leading to less accurate results later.

Keep your balance clean, inside the draft shield and out. We recommend using a microfibre cloth or a soft bristled brush to wipe around the weighing pan to remove debris. If there are any spills, ethanol-based cleansers are effective because they evaporate without leaving a residue.

Operating a lab balance takes experience to do it properly, but Scaletec can help. Give us a call. We’d love to chat.