20 Oct An increasingly essential layer
On the 11th March the World Health Organisation declared the new coronavirus disease (COVID-19) a pandemic as it quickly spread around the world and workers not only in healthcare or emergency response but throughout society, needed protection against viruses and bacteria. Here Anles Cabrera, Carrington Textiles, explores the technology and chemistry behind the development of antiviral fabrics.
At the beginning of 2020, the idea of seeing a teacher at a school or waiting staff at a restaurant wearing personal protective equipment (PPE) to be able to do their jobs was something we didn’t imagine possible.
Over nine months later, citizens in every corner of the world have been asked – to different degrees- to wear a face covering for protection against the virus. As reported by Aljazeera back in August, at least 50 countries including Venezuela, The United Arab Emirates and Turkey made wearing a face mask when leaving the house compulsory.
Efforts then turned into satisfying the huge increased demand for face masks, so brands from around the globe including Louis Vuitton, Disney and GAP changed their production lines into making the product. According to Vogue Business, after face coverings became mandatory in the UK on public transport, the following week saw the number of mask styles selling out spike by 48%.
This need for extra protection resurfaced all the antiviral and antibacterial solutions already available in the market, and antiviral fabrics became the next thing. This technology has existed for a long time, and there are a number of alternatives available in the market.
The quest was then for textile and biochemical companies to run tests that prove the efficacy of the technology against coronavirus. The best way to do so is under the ISO 18184:2019 standard, which is used to determine antiviral activity of a textile product and is carried out by independent laboratories around the world by using a sample of the virus against the fabric to determine its effectiveness. For example, the Antiviral Finish by Carrington Textiles has been tested to the standard showing best in market results of over 99% effectiveness against viruses in 2 hours and over 98% after 50 washes at 60°C.
How do antiviral treatments for fabrics work?
The porous nature of textiles means that viruses and bacteria can be trapped within the fabric structure, which possibly lowers the risk of the viruses being transferred. However, according to various studies they can still remain viable for approximately 24 hours on fabrics, and bacteria may also replicate within the material leading to unpleasant odours, amongst other things.
Currently there are two types of antiviral solutions for textiles in the market. The most common are the chemical treatments which are based on four different technologies – silver, protein, qual salt and hybrid- and added to the fabric as a coating at the last stage of the manufacturing process by using pressure and heat.
Silver based treatments use silver ions that interact with parts of the virus blocking the biosynthesis stage and so the virus is not able to reproduce.
Protein treatments work slightly different as they mimic the mucus membrane of the nose and throat and when a virus touches the fabric it binds to the protein layer and is deactivated.
The very high molecular charge of the Qual Salt based treatment pulls in the microbe and punctures the cell wall which causes the cell to die.
Lastly, Hybrid Systems utilise a mix of silver and vesicle technology. The vesicle robs the cholesterol from the outer wall of the enveloped virus exposing its genetic material and deactivating it.
Another type of antiviral solution for fabrics is the Inherent Fibres. There are a number of fibres on the market with antimicrobial products embedded in them. They are mainly silver based with ions that deactivate viruses and kill bacteria. These fibres are added at the beginning of the manufacturing process.
The testing process
The ISO 18184:2019 standard is generally used to test for the antiviral activity of textiles. In simple terms, samples are inoculated with a solution containing active viral particles. The type of virus used is decided by the company requiring the test. This is allowed to incubate for a period of time after which specimens are drawn off and the number of viral particles still present is counted. Results are often discussed as a log reduction and then expressed as a percentage with figures over 80% considered to be a good performance for textiles.
As it’s accepted that viruses start to be deactivated in 2 hours, this is the time most antiviral tests will be done at.
Other antibacterial tests include the ASTM E2149, BS EN ISO 20743, AATCC Test Method 100, BS EN ISO 2064 and AATCC Test Method 147.
The difference between viruses and bacteria
Since the coronavirus pandemic affected every aspect of our lives, healthcare terms like virus and bacteria have become a part of mainstream communications. But many people use these words interchangeably without understanding they are very different in nature.
Bacteria for example are small, alive microorganisms that are made up of a single cell. They are very diverse and can have a large variety of shapes and structural features. Bacteria can live in almost every conceivable environment, including in or on the human body. They reproduce by self division, stay localised to a limited area, can be seen with a microscope and some are even beneficial for the human body.
Viruses are also microorganisms but in this case not alive. They are considerably smaller than bacteria, are very diverse and are parasitic. This means that they require living cells where they can inject their DNA to reproduce.
Are antiviral fabrics the solution to the current situation?
Some may argue that antiviral workwear will not stop the spread of the virus alone and they are right. For this a number of measures need to be taken into account, including the basic World Health Organisation’s advice on hand washing and social distancing.
But with the virus staying active for around 24 hours on textiles, being so easily spread and with economies in every corner of the world being affected, it’s important that all the possible alternatives are taken into consideration to avoid cross contamination at work and keep infection rates at bay. Antiviral fabrics are not an alternative to PPE, instead they are a complementary extra layer of protection necessary in times where safety is key.