Are Resin Printer Fumes Toxic? What You Need To Know

The United States Department of Labor identifies seventy resins based on their material composition. This list does not include branded resins and variants, such as standard, transparent, flexible, or rigid. So, that raises the question: what if you breathe in the fumes from one of these various resin types. Are the fumes toxic?

Resin printer fumes are toxic in unventilated spaces where the oversaturation of vapors and dust increase the concentration of harmful volatile compounds in the air. Inhaling toxic fumes can cause sensitization, breathing trouble, throat and lung inflammations, and asthma upon chronic exposure.

However, photopolymer resins used in desktop 3D printers are not hazardous if you prepare your studio properly and take all essential precautions. This guide discusses everything you must know about resin printer fumes toxicity and how to shield yourself against all dangers.

Are All Resin Printer Fumes Toxic?

Most resins have volatile organic compounds and synthetic materials. Thus, their fumes aren’t completely safe, irrespective of vapor concentration. However, all resin printer fumes are not equally unsafe. Bio-based photopolymer resins used in 3D printers are generally safe, subject to conditions.

Let us consider a practical scenario.

• You have an SLA, DLP, or LCD 3D printer.
• You choose a particular resin for your projects.
• Your printing studio at home is set up in a certain way.

Now, it is nearly impossible and wrong to generalize and assume the toxicity of the fumes of a selected resin in your studio environment without assessing every significant detail. Besides, individual exposure to any such toxicity depends on many variables.

• What is the chemical composition of the resin?
• How long is your average printing session?
• What is the frequency of your printing cycles?
• Does your 3D printer have a flawless enclosure?
• Is your studio efficiently ventilated?
• Do you use protective gear: mask, gloves, coveralls, eyewear, etc.?

Toxic resin fumes are unsafe during printing and curing as well as immediately after hardening or solidifying. Resin doesn’t cure entirely just after you complete printing a model. Hence, you must not let your guard down.

Why Are Resin Fumes Toxic?

Resin fumes contain several chemicals. Photopolymer resins are not the same as the organic substances secreted naturally by plants. Most photopolymer resins comprise acrylate monomers, TPO initiators, and optical brighteners (BBOT). Some resins may contain isocyanates in the hardening catalyst.    

Most manufacturers are fiercely secretive and firmly protect every unique product formula. Resin manufacturers are no different. However, Autodesk broke ranks and released their recipe for the PR48 Standard Clear Prototyping Resin.

Their official press release link isn’t working at the time of writing this guide. You can refer to this news from around the same time when Autodesk announced their Ember’s printing resin as an open-source formula.

Autodesk PR48 vs. Bio-Based Photo-Curable Resin

Let us compare two chemical formulas of photopolymer resins:

1. Autodesk’s Standard Clear Prototyping Resin (PR48 for Ember 3D Printers).
2. Bio-Based Acrylate Photo-Curable Resin Formulation for Stereolithography 3D Printing.

Chemical Composition of Autodesk PR48

• PR48’s photo-initiator is 2,4,6-Trimethylbenzoyl-diphenyl-phosphineoxide at 0.40%
• The UV blocker is 2,2’-(2,5-thiophene diyl)bis(5-tert-butyl benzoxazol) (OB+) at 0.16 %
• The reactive diluent is Genomer 1122 at 19.89%
• The acrylate oligomers are Ebecryl 8210 at 39.78% and Sartomer SR 494 at 39.77%

Chemical Composition of Bio-Based Photo-Curable Resin

The American Chemical Society published the details of an experiment to formulate, create, and use a photo-curable resin to make 3D printed objects. The chemical formula is similar to Autodesk’s PR48.

The experiment conducted by Vincent S. D. Voet and team made photo-curable resin using:

• Isobornyl acrylate (SA5102, Sartomer)
• 1,10-decanediol diacrylate (SA5201, Sartomer)
• Pentaerythritol tetraacrylate (SA5400, Sartomer)
• Multifunctional acrylate oligomer (SA7101, Sartomer, Mn = 1.7 kg·mol–1)
• Diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO, Aldrich, 97%)
• 2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene (BBOT, Aldrich, 99%)

Potential Toxicity of PR48 and Photo-Curable Resins

Neither PR48’s composition nor the experimented formula sheds any light on toxicity.

Autodesk issued a warning in their announcement, asking nonprofessionals not to try the chemical formula at home or in any inappropriate setting.

Voet’s experiment aimed to study photo-curable resin’s sustainability in 3D printing, not safety.  

Acrylates

Acrylates are unsafe in homes, non-industrial areas, and uncontrolled or unregulated spaces.

The toxicity of acrylates depends on the monomer and polymer structures. Acrylic acid esters are volatile and toxic if inhaled.

Refer to the relevant details and toxicity information about the structure-toxicity of acrylic monomers published by the NIH’s National Center for Biotechnology Information.

Like the toxicity of resin fumes, one cannot generalize esters and their effects on human health.

However, ester fumes can irritate your mucous membrane. Some esters are extremely toxic, like tetraethyl pyrophosphate.

The National Oceanic and Atmospheric Administration provide a concise but enlightening description of everything you must know about esters.

Isobornyl Acrylate

The bio-based photo-curable resin made for the experiment cited above uses a particular monomer called isobornyl acrylate. How safe is this substance?

Evonik Industries, a specialty chemicals company, says the substance is very toxic to marine life but has low toxicity on human health. However, isobornyl acrylate is an irritant. It causes skin allergies. 

Besides, the safety summary states that the non-biodegradable substance is not for direct consumer use. Isobornyl acrylate is only intended for use in factory settings with controlled environments and industrial ventilation. 

Isocyanates

All liquid resins, whether epoxy or acrylate, need hardening agents like isocyanates or catalysts to polymerize. Photo-curable resins or plastics that can be solidified using photopolymerization use such catalysts or hardening agents to cure when ultraviolet light is directed at specific points in the resin tank.

According to the Centers for Disease Control and Prevention, isocyanates are highly reactive.

The information, co-published by the National Institute for Occupational Safety and Health, warns that isocyanates are strong irritants affecting the respiratory and gastrointestinal tracts and the eyes’ mucous membranes.

CDC and NIOSH recommend desensitization and extreme precaution for workers who are exposed to isocyanates.

The common health hazards include respiratory and dermal sensitization, sore throat and dryness, cough, breathing problems, wheezing, nasal congestion, asthma attacks, eye irritation, and skin inflammation.

Catalysts and Agents

However, err on the side of caution. The toxicity of resin printer fumes depends substantially on the catalysts and agents used in the product and the resulting byproducts during photopolymerization, curing, and hardening. Not all catalysts and agents are toxic.

Epoxy Resin

Some 3D printer resins may use epoxy. Most epoxy resins produce toxic fumes. Inhaling such fumes causes irritation and inflammation in the respiratory tract. Some people may have allergic reactions to epoxy chemicals trapped in their mucus. Smokers are especially more vulnerable.

Users are susceptible to sensitization when exposed to epoxy resin dust, sprays, vapors, or fumes. Frequent exposure to epoxy resin fumes while being sensitive can cause severe adverse effects on health. Wearing protective gear and ensuring adequate ventilation are the only two ways to prevent sensitization.

Epoxy fumes or vapors may linger even when the resin is curing during and immediately after 3D printing. Exercise caution throughout the curing and solidifying process, even when the post-print model is undergoing further hardening.

Resin Printer Fumes Are Unsafe for Hobbyists

The Occupational Safety and Health Administration says printing is among the industries where work-related asthma due to isocyanates is common. The list of jobs and processes also includes plastic manufacturing.

Berkeley’s published material safety data sheet for West System Inc., a leading resins and hardeners manufacturer, warns that inhaling vapors generated through heating epoxy causes nausea and headache.

Prolonged inhalation can cause respiratory allergies and irritation or inflammation in the lungs. Even temporary or limited exposure to epoxy fumes aggravates pre-existing respiratory diseases.

The datasheet also warns of itchiness, irritation, redness, and rashes on the skin. Eye irritation is common, too.

Chronic exposures are unlikely for hobbyists unless someone is on a printing overdrive. 

However, acute inhalation is more likely for beginners, enthusiasts, and even veteran home printers.

Workers in industrial facilities wear protective gear and function in closed, controlled, and well-ventilated environments. Besides, companies manage their operations with complete knowledge of workplace hazards depending on the materials they handle.

For impeccable safety and preventive measures, it is pragmatic to accept that all resin printer fumes are unsafe for home users, albeit to varying extents. Hence, you must prepare the studio and protect yourself accordingly.

Steps To Prevent Inhaling Toxic Resin Printer Fumes

Follow these steps to prevent inhaling resin printer fumes:

• Choose a 3D resin printer with an impeccable enclosure.
• Maintain the print chamber to prevent cracks.
• Use low or non-toxic, bio-based, and water-washable resin.
• Wear a mask, gloves, well-fitted overalls or sleeves, and reliable eyewear.
• Set up a printing studio with adequate ventilation and temperature control.
• Use a room with windows or one ducted to an effective air handling unit.
• A suitable space is a room with natural cross-ventilation.  
• Keep isopropyl alcohol bath on standby to submerge printed resin objects.
• Plan short print cycles and allow fresh air to cleanse the indoor environment.
• Exercise caution throughout printing, curing, handling, and post-print processing.

3D printing materials are still an evolving spectrum. The market is already flooded with more than a dozen materials. Yet, many users and sellers don’t have all the relevant data about material composition.

Take the example of thermoplastic filaments. PLA fumes are not as smelly or toxic as ABS vapors. ABS filaments generate styrene fumes. Nylon filaments and powders also generate fumes, but the smell and toxicity vary depending on the composition. Neither ABS nor nylon is deemed as safe as PLA.

Likewise, the various resin types, their distinct chemical compositions, and the use of myriad catalysts, agents, or substances make it nearly impossible to make a sweeping judgment about the toxicity of their fumes.

It is imperative to judge each resin, printing technology, the actual quantum of fumes or vapors generated during a print cycle, and how a particular material cures in different circumstances.

Circumstantial elements play a role, too. Bio-based resin fumes are not highly toxic at room temperature in well-ventilated spaces. However, the toxicity can change depending on the temperature and pressure inside a room.

Like ventilation, a few other specific factors in a printing studio can also influence how unsafe resin printer fumes are.

How To Eliminate Toxic Resin Printer Fumes?

Not every enthusiast can dedicate an entire room to a 3D printing studio. Also, a spare room may not have natural cross-ventilation, adequate windows, or even sufficient ductwork in some cases. Special arrangements are often a nonstarter in these scenarios.

You can eliminate toxic resin printer fumes using two different methods: extractors and hoods. Neither approach needs any complex infrastructure or gigantic installation. Many industries use either or both, and innumerable professionals have these at their home workshops.

Fume Extractors

Fume extractors are ideal for 3D resin printing. These portable machines tend to have flexible arms. You can move and direct or redirect the arm to a particular area where you want to eliminate the toxic fumes or vapors.

Some portable extractors have more than one flexible arm, so you can target two or more spaces inside the room to get rid of fumes swiftly and effectively. Although a fume extractor has limited coverage, you can use it precisely where necessary.

For example, you can use a portable extractor to clean your immediate breathing space when processing or finishing cured resin. You can aim the arm directly towards the printer, build plate, or resin tank during printing.

Sentry Air Systems Inc. makes three different portable fume extractors with varying valuable features.

You can also check out the Air Impurities Removal System Portable Air Cleaning from Amazon.com. It comes with four low-cost replaceable filters and operates quietly. 

Fume Hoods

Fume hoods are suitable for fixed installations. You can choose one large enough to cover the entire immediate surrounding area of your resin printer. Also, you may compare ducted and ductless fume hoods for your 3D resin printer.

Voet and his team used a fume hood for the experiment cited above in this guide while adding the photo-initiator and optical absorber to polypropylene.

Sentry Air makes ductless fume hoods, so you don’t need any ductwork, ventilation, or a window to serve as an outlet. Choose unit configurations, such as size, and additional features like walk-in or custom, depending on your needs.

You may also consider the ixaer VD 650 Fume Hood from Amazon.com. The 25.5 inches (90.27 cm) wide hood has both HEPA and carbon filters. It stands 33.5 inches (118.59 cm) tall with a depth of 21.6 inches (76.46 cm).

Conclusion

Rare or occasional limited exposure to resin printer fumes is unlikely to have any severe effect on your health. Plus, rooms with sufficient ventilation are relatively safer even if you use resin printers routinely.

However, the safest approach is taking the precautions recommended in this guide to prevent inhaling resin printer fumes and to use a portable extractor or ductless hood.