If you’re considering printing or already printing with vat photopolymerization 3D printing technologies known as “resin printers”, you’ve probably heard that the UV resin used in the printers is toxic.
Resin printers are extremely popular because they offer high detail and high resolution on even very small prints that filament printers simply cannot reproduce.
That aside, is the resin in your 3D printer toxic?
The short answer is yes. UV-curable and other resins are highly toxic. However, it’s typically about the same amount of harmful as bleach and many other household cleaning agents. It’s toxic and poisonous if inhaled, but you normally wouldn’t inhale it – so it’s safe to have in your home.
Why Is UV Resin Toxic?
UV-curable resin is the primary resin used for stereolithography printing methods, which is what your resin printer is doing.
The liquid resin used in those printers is hardened using UV lasers, which are able to print fine details in a vat of liquid resin, creating precise details by simply hardening the material necessary for the print.
That resin is always “toxic” in that it can cause skin irritation, eye irritation, lung irritation, and may cause other problems.
Almost all resins give off fumes containing volatile organic compounds (VOCs) which can be harmful to the throat or lungs.
For this reason, it’s always important to work with liquid resin in a well-ventilated room and preferably with an appropriate mask. Eyeglasses are also recommended, as those same fumes can irritate the eyes.
Volatile compounds can irritate your eyes, nose, and lungs like other chemical products you already use in your home.
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For example, bleach, window cleaner, glue, spray paint, and drain cleaner all come with the same warnings. They’re “toxic” but, like UV resin, they’re only a danger if you don’t use them as directed.
Short-term exposure to fumes from the liquid resin can result in dizziness, headache, irritation of the throat, and coughing.
Long-term exposure may include a risk of cancer, but as these compounds are relatively new to the market, that is not well-studied.
Most liquid resins are poisonous if inhaled. Unlike other forms of UV resin toxicity, the material remains toxic after hardening.
This means that if you, a child, or a pet swallows cured resin, it’s still important to go to the hospital immediately. This is why 3D printing resin is never food safe.
In addition, some people choose to use organic resin for dishware and food-safe projects. Unfortunately, organic resins are normally more poisonous than synthetic resins.
Any type of UV-curable resin will cause problems when ingested. These problems may include irritation of the stomach and esophagus, toxicity or poisoning, liver and kidney damage or failure, and nausea or vomiting.
This extends to after the resin is cured, although curing will reduce the impact that ingestion has on your stomach, as less of the chemical compounds will make contact with your stomach. Still, it is important to go to the hospital.
3D printing resins can irritate or burn the eyes and skin. This is often because of ingredients like isooctyl acrylate, plasticizers, HDODA, epoxidized soybean oil, HEMA, etc., which can all burn the skin.
It’s important to use gloves when handling liquid resin directly, such as if you want to rescue something from a vat after dropping it, and when handling prints before the post-cure.
In addition, you’ll want to flush the skin or the eyes with water if you expose either of them to uncured resin.
Many types of UV resin are toxic to the environment and may have significant harmful effects, especially on marine life. This means you should never pour liquid resin down the drain or flush it in the toilet, as it may kill plant and animal life.
In addition, exposure to resin may result in unexpected side-effects, like reduced fertility in people or animals who ingest it – although side-effects will heavily depend on what type of resin you’re using.
Some “bio resins” are safer to handle and use. However, they should always be treated as toxic waste.
If you wish to dispose of UV resin without curing it first, bottle it and take it to your local toxic waste disposal – which is likely at the dump and at some disposal points where you might also take batteries or motor oil.
Different Kinds of Resin
Here, the resin can be made of plant or synthetic materials. It includes any group of liquids that can be converted into polymers with UV light, known as “UV hardening”.
Depending on where you purchase your resin, it can be epoxy or acrylate-based. However, most desktop 3D printers use acrylate-based resin.
If you’re working with prototyping resin or are printing in a commercial setting, it’s much more likely you’re using epoxy resin. You’re probably more familiar with this as “glue”.
And, if you’ve ever used glue in an enclosed room, you know that exposure to those fumes can cause you to become dizzy and lightheaded. Most types of resin are much the same.
Even within that, the chemical makeup of resin can vary significantly. The basic components are all monomers, oligomers, and photo initiators, which form the building block of a resin that cures to a polymer under UV light.
Yet, any resin will have compounds added to impact the appearance, strength, smell, or even weight. So, the level of toxicity can vary significantly between resins.
5 Safety Precautions To Follow
UV resin is significantly less harsh than more traditional epoxy resins. This means that you’ll need fewer safety precautions when working with it. However, it’s still important to take safety precautions and to ensure you and your home stay safe.
In addition, you should always make sure you’re working in a clutter-free area and on a non-porous surface.
1. Use Resin in a Well-Ventilated Area
It’s always important to use a resin printer in a well-ventilated area. That’s even true if you intend to leave the printer on while you aren’t in the room.
Leaving a resin 3D printer running in a closed space can cause fumes to build up. When you enter the room again, it can be dangerous to do so.
For this reason, you should always ensure you have adequate ventilation. Often, having an open window is good enough to ensure safety.
In other cases, hobbyists prefer to use a ventilation hood over their 3D printer to remove potentially dangerous fumes. Others use fans to direct fumes away from people and towards an open window.
Whatever you opt for, it’s important that you be aware that if you can smell the resin, you are being exposed to fumes and potentially to volatile organic compounds which could be harmful to you.
In addition, it’s important to keep in mind that pets, especially cats and birds, can be significantly more sensitive to VOCs than most people. Therefore, if you keep birds, you’ll want to take extra safety precautions and use a fan or a ventilator.
2. Avoid Contact with Skin and Eyes
Almost all 3D printing resin is a skin irritant. In some cases, UV resin is enough of an irritant to cause light burns or rashes. That will harm the skin and the eyes.
Here, it’s important to avoid contact with the skin and eyes.
If you can’t, be sure to flush the contaminated area with water to minimize damage and remove any remaining resin. This may not prevent a burn but it will prevent the burn from getting worse after initial contact.
If the sensitive area continues to get worse after flushing with water, contact your local hospital.
It’s also important to note that UV resin can be an allergen. This means you have an allergic reaction after exposure to resin.
If you haven’t previously checked for an allergy, it’s important to pay attention for hives, rash, and spreading redness – which could result in a serious histamine reaction and hospitalization.
3. Wearing Protective Gear
Most UV resin manufacturers recommend that you wear protective gear while handling and using their products.
Others state that simply keeping a well-ventilated space and avoiding contact with skin and eyes is enough.
Protective eyewear is important to prevent splashing and for keeping fumes from contacting your eyes. Any pair produced for chemical and laboratory usage is good enough.
However, a standard pair from a hardware store, intended to stop wood particulates, are not good enough. Look for goggles with UV protection if you intend to use them around the active 3D printer.
A respirator mask will prevent fumes from entering your lungs and from irritating the mouth, nose, and lungs.
Here, you should have an N95-rated mask or better. If you’re sensitive to UV Resin fumes, using epoxy resin, or want to be extra careful, you’ll want a respirator with an organic vapor cartridge instead.
These are reusable, meaning you’ll only have to buy them once and then replace the cartridges as directed. In most cases, a good reusable mask will cost about $30.
Protecting your skin from resin burns is important, whether you’re handling resin or handling semi-cured (before post-cure) prints.
Here, it’s important to purchase gloves with chemical resistance. This means choosing nitrile or neoprene gloves.
Why? Latex won’t actually stop chemicals from resin. If you get resin on latex gloves, take them off immediately and wash your hands. From there, you should leave the gloves in the sun to cure before you throw them away.
However, it’s important to note that at any point where you get resin on your gloves, you should throw them away.
It’s also a good idea to always cure the resin on the gloves before putting them in the trash to reduce environmental pollution. Most hobbyists also double-bag their gloves for the same reason.
4. Checking Your Resin’s Recommendations
There can be considerable differences between UV resin types.
For this reason, it’s always a good idea to read the safety sheet and recommendations that come with the resin you purchased. For example, many resins are listed as minimally toxic but still irritate the skin and eyes.
You’ll also still want to use them in a well-ventilated area. Others are very strict about the fact that you must use a respirator and eyewear when working with the chemicals.
In addition, if you have a desktop printer in an area with children or pets, it may be important to deliberately source resins that are less harsh.
For example, choosing a less harsh resin is a good idea if you have ventilation in place but can’t guarantee that your pet won’t get near the printer.
5. Dispose of It Safely
It’s always important to dispose of resin safely.
Often, that means taking steps to cure the resin before disposing of it. In addition, you may have to take your resin to a chemical waste disposal.
Most areas have designated dumping areas for toxic or chemical waste. You can look up the correct site for your city or state online.
Here, you’ll normally be asked to bottle your liquids and submit them sealed to the site, sometimes for a small fee, but most often for free.
You can always dispose of cured resin as part of your household waste. However, many people recommend double bagging it in ziplock bags to prevent environmental contamination.
To cure your resin, leave it out in the full sun until it’s fully hardened. Then, bag it and dispose of it in your household waste.
This is the best option for disposing of lightly contaminated objects such as gloves. In addition, it may be more convenient or more efficient than taking liquid resin to a disposal site.
Alternatives To Toxic UV Resin
If you want a less toxic UV resin, you can choose one of a number of “bio” resins on the market. These are made by some of the world’s largest 3D printing companies.
However, “bio” does not mean “non-toxic”. If you choose any of these alternatives to UV resin, you should still exercise caution, read the data sheet, and dispose of the materials carefully.
1. Elegoo Plant-based Rapid UV-Curing Resin for LCD 3D Printers
Elegoo’s Plant-based Rapid UV-Curing Resin is plant-based and made from soybean. It is fully BPA-free, low-fume, and low-odor, which makes it ideal for printers in homes.
It also works with any UV light at 405nn, meaning it works with most resin printers on the market. It also comes in four colors at $18.99 per pound.
2. AnyCubic Plant-based UV Resin+
Anycubic’s Plant-based UV Resin+ is a low-odor, low-fume, and BPA-free resin based on soybean oil. With hardening at 365-405nn UV wavelength, it has a wide range of compatibility, and does work with nearly any 3D printer.
Like other soy-based resins, it is still a major skin irritant, and you still have to wear gloves. It also comes in 5 colors and costs $74 per 1000 grams.
3. eSun PLA Resin
eSUN’s PLA resin was one of the first soy-based resins on the market and is still one of the most popular options.
This soy-based resin is also certified for safe use in printing toys, is drillable, and has low odor during printing. It also comes in 11 colors, from $29.99 per 1,000 grams.
4. 3Dresyns Bio D
3Dresyns Bio D is a biodegradable resin based on soy.
It’s also odorless, environmentally safe and, and compatible with nearly any SLA DLP printer. However, you do have to use gloves and goggles while printing with it.
In addition, at $180 per 1,000 grams, it’s one of the most expensive options – although it’s one of the only ones that are fully biodegradable.
UV resin is toxic and may cause irritation to the skin, eyes, and lungs. In addition, if swallowed, UV resin can cause major toxicity including organ failure. Like many other household chemicals, you have to follow the safety sheet provided with your resin in order to use resin safely. However, if you follow those instructions, there’s no reason why you can’t safely print with UV resin.