Liquid resin is the main material used in resin-based 3D printing, such as stereolithography (SLA), digital light processing (DLP), or liquid crystal display (LCD). In a nutshell, these use a UV laser, projector, or LED array respectively to trace the shape of an object onto the surface of a photopolymer vat. The resin then cures to form layers of the print, and the entire process is repeated until it’s a complete 3D object.
Using a resin 3D printer is very different from using a fused deposition modeling (FDM) printer for many reasons, including the unique properties of resin itself. Resins used in 3D printing have toxins and need to be safely handled, stored, and disposed of. Not surprisingly, the toxicity of resin makes the whole process of disposal more complex than with FDM and plastic filaments.
Each resin has a slightly different formulation, and you might personally find certain a resin or resin brand particularly irritating – more so than other brands. Nevertheless, the proper handling and disposal will be the same regardless of which resin you pick.
In this article, we’ll guide you through the safety precautions that you should take when handling resin, how best to store it, and finally, how best to dispose of it. Let’s kick things off with a discussion of potentially milder resin options.
Be a good citizen and read on!
A Note On Eco-Friendly Resins
There are a lot of resin options available. If you’ve noticed that you’re particularly sensitive to resins either from accidental skin contact or to the fumes, there are a few options you could try. Generally, “environmentally friendly” resins may have lower concentrations of common irritants and volatile organic compounds (VOC). Noteworthy examples include Anycubic’s line of plant-based resin, and Elegoo’s range.
With these resins, you also have the benefit of purchasing a product made with renewable resources rather than the typical petroleum sources. Keep in mind, however, that bio-based is not the same thing as biodegradable. So, you shouldn’t throw these resins, cured or not, into the compost. At the end of the day, resin is still resin regardless of where it’s derived from.
Even while using these “eco-friendly” resins, all the safety and disposal steps discussed below are still applicable. If you’re ever unsure about the proper usage or disposal protocols – for resins or any other chemical – always follow the manufacturer’s instructions and material safety data sheets (MSDS).
Resin, eco-friendly or not, is toxic to humans and to aquatic life, which makes proper handling and disposal super important at all stages of printing. So let’s get into what to do, and what not to do.
Safety
When dealing with resin, you should always wear your PPE: personal protective equipment. Resins can harm your skin and leave nasty rashes. So whenever you use resin, always wear gloves! A lab coat or apron is also advised to prevent resins from getting onto your clothes and then soaking through to your skin.
In most places, you’ll be able to choose from latex and nitrile gloves. The latter are better for handling resin because they’re more chemically resistant and, of course, not a common skin allergen like latex.
Apart from the gloves, you may also want to wear protective glasses, which keep you safe from splashes that could cause some serious eye damage if you’re unlucky. It won’t cost you much to pick up a pair, so from our perspective, it’s a no-brainer. You can also use a respirator to prevent breathing in any fumes from resin (a typical medical mask cannot offer much protection against chemical fumes).
Storage
When you’re not using your resin, it’s important to store it correctly. As resins easily react with UV light resin manufacturers always use black, light-proof containers.
However, it’s also recommended that the containers be kept out of the sun. Putting the container in a cabinet or in a dark place is best.
Ideally, resins and other chemicals should be stored in well-ventilated areas to prevent the build-up of volatilized chemicals. While we don’t expect you to have your at-home fumehood, consider storing your resin jars either in a tightly sealed, leak-proof secondary container or somewhere that gets lots of air movement.
During Printing
Pre- and mid-printing phases are simple when it comes to handling your resin safely. The most important thing is to make sure you’ve got your gloves on when initially pouring resin into the vat or if you need to add more during the printing process.
Spills can happen when you’re pouring resin, so let’s discuss what to do if that happens. If you get resin on your skin, immediately wash it thoroughly with water and a mild soap. In the case that you develop a rash, call your doctor. If you got resin on your clothing, make sure to wash it before you wear it again. In the end, a spill usually isn’t that big of a deal if you have the proper gear to clean it up.
Before you start doing anything with resin, make sure you’ve got some isopropyl alcohol. This will ensure you’re prepared if a spill happens on your workspace or other equipment. Cleaning with alcohol ensures all your spilled resin will be removed properly. You’ll also need alcohol for cleaning the vat and the build platform, so make sure you’ve got at a big bottle nearby!
After Printing
The post-printing phase is a bit more involved. It includes removing your print from the build platform, cleaning the vat and the build platform, and also pouring the resin back into its container.
Once your print is done, we suggest you lay some paper towels down around the printer. This will prevent the resin from going directly onto the surface you’re working on. Of course, wear gloves when pulling the build platform out of the printer, as well as when you’re cleaning it with alcohol.
We won’t go through the process of post-processing here, as that’s beyond the scope of this article. If you’re interested, you can read more about post-processing resin parts in our dedicated article.
Water-Washable Resin
It is important, however, to briefly discuss water-washable resins. They simplify the cleaning of resin 3D printed parts but leave residual rinse water behind that contains substances that are very hazardous to you and the environment.
Leftover rinse water should not be poured down the drain. Any residual resin in the water has to be cured prior to disposal, which we’ll discuss in detail below.
Clean Up
After a print’s done, the vat typically contains some leftover resin. This resin can be reused, so definitely put it back into its container.
Open up the container, and put a funnel into the opening. It’s ideal if the funnel has a mesh filter.
Slowly pour the uncured resin from the vat back into the container until the vat is empty. Then use paper towels with alcohol to wipe out any remaining uncured resin. Be gentle when wiping the FEP film so that it doesn’t get scratched.
Curing
Curing is absolutely critical when it comes to resin disposal, so let’s get into what it is and how to do it. When you buy resin, it comes in an uncured (liquid) form, which is good for printing but also toxic!
Thankfully, curing is pretty simple and involves heating the resin up or exposing it to sunlight (or another source of UV light) until it’s completely hardened. Basically, cured resin is safe resin.
Once you’re done with printing, your gloves will have some resin on them, as well as the paper towels used. We suggest putting your gloves and paper towels into the sun, if possible, to cure the leftover resin so that you can dispose of that waste with the regular trash.
If you aren’t in a sunny place, there are a number of other ways to cure the resin from your gloves, paper towels, bottles, and prints. All involve turning up the heat, literally, with heat or UV lamps.
Curing simply takes time and depends on the type of resin you’re using. The manufacturer should have information printed on the bottle about recommendations, as well. The most important thing is that the resin dries completely from whatever surface it’s on.
Regarding water-washable resin, prior to disposing of the residual rinse water, it should also be exposed to either sunlight or UV light. Depending on the intensity of the sun, at least a half-hour is needed. Any residual resin in the water will form as solid particles, which can be strained from the water and disposed of with regular trash. After that, the rinse water can be safely thrown out.
Disposal
In a case where you’d like to throw away a failed print (and the memory of it), be sure to cure it first. When cured, the resin isn’t dangerous anymore, hence why the parts can be touched without gloves and therefore disposed of with the regular trash.
The same goes for resin containers that are either emptied or contain some leftover resin. Always let the resin cure before disposing of it. Simply open up the containers and leave them in the sun or a warm place until they’re completely dry.
Never pour the resin into the drain as it can end up damaging your pipes and, even worse, the environment.
Another option for disposing of resin is to let the professionals do it. Contact your local waste or recycling center to see if they have the capacity to dispose of your waste safely.
Dos & Don'ts
Here’s a quick “Dos and Don’ts” list for you to make sure you’re handling your resin responsibly.
Do:
- Wear gloves and goggles when handling resin throughout your 3D printing process.
- Cure your failed prints, used gloves, used cleaning supplies, and resin containers before disposing of them with the regular trash.
- Contact your local waste or recycling center for help, if needed.
Don’t:
- Handle resin without gloves. (This is really important!)
- Pour uncured resin down the drain.
- Throw away uncured resin.
License: The text of "How to Dispose of 3D Printer Resin" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.