Analytical Balance Features: Percentage Weighing

Percentage weighing is one of the most common weighing features that can be found on an analytical balance – but what is it? And how can it be used? This blog takes a look at how percentage weighing can be used in the lab, and how it can make weighing out multiple subjects faster and more efficient.

What is percentage weighing?

Percentage weighing is an advanced feature that is found on many types of weighing scale and balance, and essentially involves weighing an item as a percentage of an overall pre-set reference weight.

The best way of explaining percentage weighing is by thinking of a cake mixture - consisting of flour, sugar, butter and eggs – which in total would add up to 100%. To make weighing out these ingredients easier and faster, it is better to weigh everything in the same bowl or container. Percentage weighing would allow you to put in 100 grams of butter, which could be relative to 30%, and then 100 grams of sugar which would make up 60% of the finished batter mix, and so on. 

What are the benefits of using percentage weighing?

Percentage weighing makes laborious weighing tasks quicker and more efficient, particularly if they have many different ingredients. Users can add all ingredients into one container placed on a scale or balance, which means they do not need to use multiple bowls during the weighing process, saving time on cleaning down after use.

Percentage weighing also ensures that your subjects are kept completely uniform, which is absolutely crucial to chemical, pharmaceutical and materials testing industries where the wrong ratios of ingredients can be dangerous. 

What is percentage weighing used for in a laboratory?

Pharmaceutical production

In the pharmaceutical industry, percentage weighing functions are crucial for ensuring medicines such as paracetamol have the correct amount of chemicals in them. It’s important that chemicals are weighed using percentage weighing as the incorrect ratio of ingredients can give different effects. Too much of a certain substance can be dangerous, whilst too little can give limited desired effects. 

Quality control

Percentage weighing functions are commonly used for quality control, where it may be difficult and time consuming to individually check multiple subjects manually. For example, a pharmaceutical company may want exactly 100 pills in each of their containers, but this would not be efficient to do by hand. Instead, users can enter in the correct percentage weight of a container with 100 pills inside, and then check to see whether other containers are over, under or at the correct percentage level.

Chemistry and materials testing

Percentages are fundamental in chemistry as the ratio of solutes and solutions will determine the outcome of an experiment. A good example of this is in the concrete making process, which is a composite material made up of several different ingredients including water, cement, air and aggregates (this could be sand, gravel, or crushed stone). The ratios of ingredients will completely change the density of the concrete, which can impact strength, permeability and flexibility.    

How to use percentage weighing

Entering percentage modes differ with every balance, but it’s usually straightforward to set up and get started. It is commonly found in the weighing mode menu or sometimes as a unit, but it’s always best to read you manual to understand how it works for your scale or balance.

Before you begin, you should know what the reference weight should be. The easiest way of doing this is by simply weighing a premade full mixture or item and noting down the weight. Also, if weighing using a container, remember to tare of the empty container weight. Once the percentage mode has been started, simply enter in the reference percentage weight and begin weighing.

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