How is it done? 3 methods to analyze textiles and fibers

We recently conducted a market survey which has shown us that there is a high demand for reliable textile analysis methods. People don’t want to solely rely on textile labels and information provided by suppliers anymore, but instead wish to conduct their own tests.

The need for textile analysis is also growing with an increasing amount of textile waste. Identifying fibers and recycling them accordingly is becoming more crucial than ever.

Our technology allows you to conduct tests quickly, non-destructively and on the go. But which other ways are there? What methods are used in laboratories around the world?

Textile analysis methods used in labs

To identify different types of fibers a range of tests can be performed. This includes solubility tests, burning tests, staining tests, and microscopic tests. The current methods to analyze fibers are generally carried out in laboratories. Usually, it requires sending samples to a lab which will often be destroyed due to the nature of the testing. The process can take several days, and even though it is a very precise method, it comes with a great time delay and high costs. Some companies trust in internal laboratories, however, equipping and staffing such facilities also comes at a high price. Today we are going to take a closer look at burning and solubility tests. How are they carried out and how do they differ from each other?

Burning tests

During burning tests, the fiber is identified by noting things like the smell, color, shape of the ash, and the speed at which the fibers burn down. As every fiber behaves differently this is a fairly simple and very reliable way of testing textiles. Did you know cotton fibers, when burned, smell like burning paper? Silk, wool, and viscose on the other hand smell like burned hair.

In general...

• The fabric is a natural fiber if the ash is soft and it smells like burned hair or paper
• Cellulosic fibers (like cotton, linen, and rayon) burn rapidly with a yellow flame, when the flame is removed, there is an afterglow, then soft gray ash
• Most synthetic fibers both burn and melt, they also tend to shrink away from the flame
• Synthetics burn with an acrid, chemical, or vinegary smell and leave a plastic bead
• Nylon smells slightly sweet and polyester smells like vinegar when burned

© [Anna Kosolapova] / Adobe Stock

Solubility tests

There are chemical differences that exist between textile fibers. Solubility tests allow you to distinguish them in a more fundamental way than you would be able to with burning tests. Testing via solvent is mostly effective when it is used as a technique for eliminating and cross-checking.

So, for example...

• When treating silk and wool with cold concentrated hydrochloric acid, silk fibers dissolve but wool fibers do not
• If you were to use sodium hydroxide solution instead, it would annihilate both the silk and wool samples, as it is known to destroy animal fibers
• Cotton is soluble in 70% sulfuric acid solution and cuprammonium hydroxide
• Polyester is soluble in heated meta-cresol solution and heated ortho-chlorophenol solution.

This shows that it is crucial to select suitable solvents when conducting these tests, as the identification of the fibers is based on their solubility in different chemical solutions. There is no one solution that can be used for every fiber.

© [AlexPhototest] / Adobe Stock

How we simplify textile analysis

Our handheld device, the SenoCorder, enables you to analyze samples wherever you are. The technology behind the device, Material Sensing, is based on NIR spectroscopy and chemometrics. It turns two decades-old laboratory methods into a solution that fits into the palm of your hand. The samples you measure are not destroyed during analysis, and you receive results instantly. The SenoCorder enables you to identify materials, e.g., whether a fabric is made from cotton, polyester silk, or wool. It also allows you to quantify the material composition, telling you the amount of a certain fiber present in your sample, e.g., 22% cotton and 78% polyester. The handheld device simply needs to be placed on the textile you want to measure, and the analysis starts at the touch of a button.

Comparing current methods with Senorics' technology

Now that we have looked at laboratory analysis methods as well as our Material Sensing technology, it is time to conclude. What are the advantages and disadvantages of each testing method? Will all the methods we covered today stand the test of time, or do certain methods outshine others?

All the methods described have their place in the world of textile analysis and are useful depending on the area of application. Tests conducted in laboratories, such as burning or solubility tests, have the advantage of being very accurate. There is a reason that they take several days and for certain situations, where a very high accuracy is needed and there isn’t any time pressure, these kinds of tests will remain a great choice.

However, in many other situations where all you need is a reliable result that you can access instantly, mobile textile analysis is becoming more and more desirable to the industry. It saves money, time, and resources. It can be used to pre-sort textiles to decide which samples might need in-depth testing at a laboratory, or it could be used to avoid laboratory testing all together.

What do you use textile analysis for? Have you ever considered switching to an easier solution?