Silver is a fast microbe killer

The ancient Romans already used silver coins to clean dishes from microbes.

Global Handwashing Day will be celebrated again on 15th October. The pandemic this year has really driven home the importance of handwashing, and it has undeniably raised public awareness of good hygiene practices.

Microbes, such as viruses, bacteria and moulds, spread from person to person through direct human contact and from various surfaces with about equal likelihood. These microorganisms and viruses end up in our mouths and eyes as we constantly touch our faces – about twenty times an hour – without even realising it. Surfaces thus play a significant role in the spread of microbes.

Silver has inherent antimicrobial properties, i.e. it kills microorganisms and viruses. The ancient Romans already used silver coins to clean water jugs from microbes, and now we treat architectural hardware, furniture and other products with silver to stop microscopic organisms and viruses from growing.

Abloy is a member of the HygTech Alliance, a collaboration of six Finnish companies, which has created the world’s first wide range of hygienic products for public spaces. Abloy’s fellow members in the alliance are Isku, Korpinen, Lojer, Oras and Teknos. ABLOY ACTIVE is one of the products we have developed in the HygTech collaboration. It is an antimicrobial coating containing silver that has been designed for architectural hardware.

I discussed with Kari Soljamo about the antimicrobial properties of silver. Kari Soljamo is a Ph.D. in Chemistry and works as a development manager at Isku, where he has been strongly involved in the product development of antimicrobial furniture and co-operation with the HygTech Alliance.

1. How is silver used for hygiene purposes?

“There are a number of different antimicrobial additives which contain silver. It’s usually a chemical compound which contains silver. In the HygTech Alliance, for example, we use in many applications silver phosphate glass, an inorganic glassy substance that contains silver. Very fine powder of silver phosphate glass is mixed into the product, such as powder coating, laminate or paint. The target is that all Hygtech Alliance members use same antimicrobial technologies in their materials whenever possible.”

“There are also applications in which silver is used as metal, such as fabrics where fibres are coated with silver.”

“In all applications – regardless of which chemical compounds silver is mixed into the material – it is the silver ion [the electrically charged atom] that affects the microbes when it comes out of the product with the moisture. The compound can be zeolite, silver chloride or silver phosphate glass, for example.”

2. How does silver work against microbes?

“Silver is harmful to microbes. We could even say it’s a rather diverse killer, as it works on at least 600-650 microbes.

“Silver affects bacteria, for example, in at least three ways:

a)        silver binds to and reacts with the bacteria’s proteins, thus inhibiting metabolism and energy production
b)        silver damages the cell wall, causing rupture
c)        silver binds to the DNA, which damages it and prevents the bacterium from replicating or multiplying.”

“All these occur relatively quickly, depending on the conditions and the antimicrobial material used. We have found that for example Staphylococcus aureus bacteria that are common in hospitals as well as E. coli bacteria have been eliminated on silver-containing antimicrobial surface within 20-30 minutes under laboratory conditions.”

3. Does silver work against the virus of the current pandemic?

“We can’t yet claim that silver is effective against the current SARS-CoV-2 virus. In order to make a claim regarding a particular virus, the effect of an antimicrobial surface against that virus must first be examined. The security classification of the SARS-CoV-2 virus currently prevents commercial laboratories from using it. Preliminary tests using standardized methods have shown that antimicrobial surfaces containing silver are effective against feline coronavirus which has been used as a model virus for SARS-CoV-2. There are, of course, various preparatory commercial development projects underway across the world.”

“Antimicrobial surfaces have already been studied quite extensively. Approximately four thousand scientific studies have been published on the subject during the past 10–20 years. We can assume that interest in different antimicrobial materials and surfaces will increase in the future, as the role of surfaces is pivotal in the spread of microbes.”

Good hand hygiene is everything

Silver coating is an effective tool in preventing the spread of infections, but it’s not sufficient by itself. Good hand hygiene is as well one of the most important ways to reduce the risk. We must also make sure we keep sufficient distance from each other and arrange safe premises and working conditions. Preventing the infection from spreading requires various actions.

We will be posting more hygiene-related blogs this autumn. Did you find this blog interesting? What cleanliness-related topics would you like us to address? Would you like to suggest a particular approach to a topic? Send your suggestions by email: marketing@abloy.com.

You can read more about antimicrobial coatings on our ABLOY ACTIVE website.

Towards a more hygienic future!

Timo Tallus
Head of Product Management
Abloy Oy

Timo Tallus, Abloy	Kari Soljamo, Isku