Digital Printing
The odourless challenge: Managing print emissions
refl ect the airborne emissions generated during the printing process itself , as they may still have potentially harmful airborne emissions that need fi ltering from print processes. This is especially concerning as some cannot be seen and are odourless. For example, some eco-UV inks are often categorised as odourless, but the safety data sheets indicate that volatile organic compounds (VOCs) are present, such as morpholine and benzyl acrylate.
ByJohn Twigg, senior key account manager at Donaldson BOFA
I
n industrial printing, airborne by-products can be generated. These particulate and gaseous organic compounds can impact the work environment, equipment and print quality. Beyond their contribution to workplace environmental compliance programmes, eff ective fi ltration systems can also help to maintain a clean print operating area, which is vital for product quality and helps manage unnecessary downtime. However, managing these emissions eff ectively while providing effi cient processes that help to boost productivity can be challenging. The print industry supply chain’s response to these emissions challenges has been to develop alternatives to ‘traditional’ ink compositions, in the form of eco-ink and eco-solvent. The term ‘eco-ink’ is often applied in relation to reduced carbon footprint or end-product sustainability, but it does not necessarily
It is therefore essential that print industry operators study the safety data sheets of every product used in the print process to ascertain the workplace risk associated with fume emitted via the inks, lacquers, adhesives and solvents. Also, while much focus is placed on the solvents in inks, it is important to remember that the pigments often consist of particles on the nanoscale, which are released during printing. These particles are not always included in safety data sheets, so operators should not assume they are covered.
Despite product innovations, the key challenge for operators remains not whether they need an extraction system to fi lter the vapours and mists generated by print operations, but which technology to select. Fume extraction technology can contribute to environmental health strategies and help maintain a cleaner print area to optimise product quality. A typical multi-stage fi ltration solution includes an advanced carbon layer to help fi lter fumes associated with a wide range of emissions.
The right choice depends on the scale and nature of their operations, as well as any subsequent operations such as laser cutting and engraving for packaging. Simply moving air through a fi lter is not enough.
CHOOSING THE RIGHT TECHNOLOGY Whatever the scale, the appropriate fi ltration system must be matched to manage the print processes. The right solution will both fi lter potentially harmful airborne contaminants from the workplace and contribute to a clean production environment. This means that the extraction system must eff ectively balance air fl ow rates with a fi ltration architecture that delivers suffi cient ‘dwell time’. This will allow the system to capture fi ne particulate matter and volatile organic compounds (VOCs) from solvents and coatings.
Dwell time is how long the air being extracted stays inside the fi lter or scrubber unit. Adequate dwell time is important for two reasons:
1. Particle capture
Fine particles, mist and fumes need time to slow down and be intercepted by the fi lter media. Slower face velocity allows better mechanical fi ltration through impaction, interception and diff usion mechanisms.
2. VOC adsorption
VOCs are usually removed by activated carbon or chemical media. Adsorption is a surface process, and the air must stay in contact with the carbon long enough for VOC molecules to bond to it. If airfl ow is too fast (low dwell time) the carbon bed becomes less eff ective. Most carbon fi lters are rated for a minimum contact time and falling below that signifi cantly reduces VOC removal effi ciency.
A fume extraction system must be tailored to specifi c processes, printer types and evolving process demands. This means that it should be fully portable and compact. Large capacity gas fi lters are also required to help fi lter fumes associated with a range of emissions, including ozone from UV applications and butanone/ methyl ethyl ketone (MEK).
People working in the print industry often refer to the ‘smell’ they experience. It would be easy to conclude that by removing these odours, it also eliminates any risks associated with airborne contaminants. However, as the safety data sheets show, that is not the case.
Printing companies must assess the associated workplace risks and consider implementing eff ective fume extraction technology in their process.
www.convertermag.com November 2025 23
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