The Effects of Different 3D Printing Resins on Air Quality in a Workshop Environment

Air Quality and 3D Printing

The question regarding 3D printing and its effects on air quality is as old as the additive manufacturing technology itself. With the rise in popularity of resin 3D printers in recent years, there has been an increase in reported health effects. These typically involve the respiratory system or skin rashes with the longer-term effects of resins still unclear.

Appropriate precautions to protect your health around resin 3D printers can range from wearing a mask, opening a window for ventilation or simply removing yourself from the environment altogether. But in some cases, the dangers are odourless and difficult to detect with the human senses. But wouldn’t it be great if there was a way to monitor air quality so that you knew when these actions might be required? Laboratory-grade air quality monitoring is not typically viable in such an application. The equipment and sampling methods are complex, it is expensive and you need to know exactly what your target parameters are, which can be difficult. But with the advancement of sensor technology in recent years, there are now very real options to provide continuous air quality monitoring on a budget.

The DesignSpark Environmental Sensor Development Kit

DesignSpark developed the Environmental Sensor Development Kit (ESDK) as an open-source hardware platform with the ability to add sensors to suit your project needs. The brains of the ESDK consists of a main board with touch screen and GPS that connects to a Raspberry Pi Linux computer. DesignSpark’s Air Quality Project is the first to utilise the ESDK’s compact and modular architecture that allows plug-and-play for sensors (no soldering and coding is optional). Three sensor modules have been released to date:

• Particulate matter board
• Total volatile organic compounds (TVOC) including temperature and humidity board
• Carbon dioxide board

The sensors on these boards have been selected by DesignSpark to ensure that the ESDK remains affordable and reliable so that it can find its way to more hobbyists like me. And this is the reason that the ESDK is the perfect fit for #activistengineering. Activist engineering aims to create positive impacts by generating awareness through actions. It is a way for everyone to work together and collaborate to contribute in small ways to big problems such as climate change and environmental destruction. The ESDK is undergoing beta testing and I was lucky enough to be selected as one of 50 testers to try it out. The kit consists of the electronics mentioned above, as well as 3D printed case parts, hardware, memory card and a power supply.

Main electrical components of the ESDK kit

I followed a build guide video to assemble the kit and it took me about an hour using basic tools. The design of the PCBs, connectors and cases is very well thought out and it assembled easily with no modifications. I also opted to make some aesthetic design changes to some of the cases to suit my project and décor. I was able to download the files in .STL format and convert them to solids in DesignSpark Mechanical before adding some chemical element-inspired design aspects. By the time I had 3D printed these parts, it added a good day to the build time. I mounted the kit to the wall of my workshop using the provided DIN rail, powered it up and connected it to my Wi-Fi network.

Completed ESDK kit mounted on wall

The kit displays the key parameters on the backlit touch screen and provides traffic light style colour coding to alert the user to different thresholds. You can view the data from the last hour by touching any of the parameters on the screen. This is really useful and I found myself glancing at it regularly when I was near it, but where the kit really shines is in its communication with DesignSpark’s Metrics cloud platform hosted on Grafana. This platform provides powerful, customisable dashboarding and alert functionalities and can also be used to share data. I made some small changes to DesignSpark’s default dashboard to include thresholds to suit my project as well as some styling changes. 

Customisable DesignSpark Metrics cloud platform

Testing Resins for VOCs

I deployed the kit in my workshop where I have resin and FDM 3D printers as well as the associated materials and chemicals. I decided to target the effects of resin 3D printing on air quality as it is the ‘smellier’ operation and it concerns me more than the FDM process. Resin 3D printing utilises photopolymer resin to build up prints in layers and in my case, isopropyl alcohol (IPA) is used to clean the finished prints. Resins and IPA are typically loaded with volatile organic compounds, so the TVOC board should be ideal to monitor that. I decided to test three different resin types and measure whether there are any differences in the TVOCs present in the workshop. I designed a small 3D model in DesignSpark Mechanical that would take around four hours to print with each of the different resins which should provide a good sampling period for the ESDK.

Test part being designed in DesignSpark Mechanical

But before I started printing, I needed to establish the background air quality conditions. I left the ESDK kit to run for a couple of days and I was relieved to see that the air quality looked pretty good. It is worth noting here that the TVOC board measurement is reported as an index value rather than a concentration or quantity value. A little research found that the Sensirion TVOC sensor used in the kit, uses an algorithm based on the conditions from the previous 24 hours to calculate the index at a point in time. The index chases a value of 100 TVOC to indicate normal conditions.

TVOC sensor index

I tested the TVOC sensor board by uncapping a bottle of isopropyl alcohol nearby that quickly saw the index reach its limit of 500 and observing the subsequent trend. It took some time to return to the 100 value. The implications of the index calculation meant that my initial resin test would be influencing subsequent TVOC results within a 24-hour period. To navigate this I decided to power cycle the kit between tests to reset the index to 100 (keep in mind that the TVOC sensor takes one hour to stabilise after powering on the ESDK). Of course, I also needed to ensure that the air quality had returned to background conditions before starting the next print. This way I would be able to make a relative comparison between different prints. I chose three different resins to conduct my tests. A regular, everyday resin, an ABS-like resin and an eco resin. The experiment did not include the parts washing process, as I already knew that this would send the TVOC index to its limit. My hypothesis was that the eco-resin would probably produce the lowest TVOCs, followed by the regular resin and then the ABS-like resin.

Different 3D printing resins for testing

I conducted the tests over three days, and the results were a little surprising. Firstly, the venting of TVOCs out of the resin printer during the print varied slightly between resins. I believe that this may be due to different densities in the air within the print chamber and the ability of the exhaust fan to replace the air within the chamber. Secondly, an increase in TVOCs was not always present when the resin printer lid was open as would be expected. But there was always a TVOC spike when the lid was removed from the printer at the end of the print. To my suprise, it was the ABS-like resin that produced the lowest VOCs, followed by the eco-resin and then the regular resin - do you get what you pay for?

Play video

Video showing the ESDK build and comparison between 3D printing resins

Implications for Managing Resin Printing Processes

The experiment indicated that the period where TVOCs are released the most is at the end of the print. This is also usually the time when the person operating the printer is likely to be present to start the processing of the print. Hence, if proper ventilation and protective equipment are utilised during this period, the effects of resin fumes are likely to be minimised. Whilst TVOCs are only an indicator for potential health effects from resins, it is a robust measurement that can provide real-time data where none has been readily available until now. Activist engineering initiatives such as DesignSpark's Air Quality Project are providing new data for a wide range of end users to change the way they approach challenges. I will be looking to add ventilation to my workshop that is controlled by the ESDK to make a small change to how I work.