UV resin printing is used in a variety of industries, from designers to engineers and everything in between. As resin is more complicated to work with, it is more commonly used by professionals and businesses than by casual hobbyists.
While more expensive and less popular than FDM printing, resin printing offers several advantages over FDM printing. For one thing, resin printing produces prints with better aesthetics.
Resin is the material that hardens or is “cured” to form a 3D printed object. But what material benefits does resin have over filament besides a better finish? In this guide, we look at the lifespan of resin. Does it last longer than filament, and what happens when you use expired resin?
How Long Can You Keep Resin?
3D printer resin has a minimum shelf life of a year. In practice, resin that is stored properly may last for up to 2 years (depending on the manufacturer) before it becomes unusable or starts to produce sub-par prints. The critical component is storage. Resin that is stored away from light will have a longer shelf life.
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Resin printers work through a process known as photopolymerization. This is where light, in the form of a laser or projector, is used to cure liquid resin into a hard plastic. Source
On a side note, check out “What Happens If You Run Out Of Resin During A Print? (Solutions)“
How To Extend The Lifespan Of 3D Printer Resin
The best way to store resin is to keep it sealed tightly in the container it came in. You also want to make sure you keep it in as dark an environment as possible.
You also want to keep it at the manufacturer’s recommended temperature range. Alternatively, you can keep it at between 5 to 30 degrees Celsius if there is no recommended temperature.
Colder temperatures are more favorable for storage. While there are many who opt to refrigerate their resins, you should avoid storing resin where you keep your food!
If you are pouring leftover resin back into its container you want to use an empty container. Avoid mixing leftover resin with unused resin as you might contaminate it. Use a sieve to filter the leftover resin to make sure you are not pouring cured resin back in with the unused resin. Mixing cured resin with uncured will render the latter useless.
Shaking the bottle every few weeks also helps to keep the resin mixed.
Does Resin Last Longer Than Filament?
FDM printers use filament to print with. Unlike resin which is liquid, filament comes in a solid length or roll of plastic which you have to melt down. Filament typically lasts for between 1 to 3 years depending on what type it is.
Filament lasts longer and is much easier to print with than resin. With that said, resin produces stronger, more durable prints compared to filament.
This is because filament bonds at a mechanical level by way of heating and cooling. Resin on the other hand bonds at a chemical level by way of UV curing (hardening). This produces prints that are “isotropic” or that are stronger both horizontally and vertically. Source
Can You Still Use Expired Resin?
The viability of expired resin depends largely on the time that has elapsed between expiration and use. The shorter the time frame, the more viable the resin is likely to be. Resin that has been sitting for a month or two after its expiration date has passed will likely be more usable than resin that has been sitting for a year or longer.
The expiry date does not necessarily mean it becomes unusable as soon as it reaches that date. It is simply a guarantee of performance up to that date. In reality, the resin will still be usable even after the date of expiry.
Rather than throw away potentially good resin, it’s much cheaper and environmentally friendly to try to use it first.
What Happens If You Use Expired UV Resin?
One of three things can happen when using expired UV resin. The first possibility is that the resin is perfectly fine and it produces a good print. The second possibility would be the resin produces a flawed print. This could be discoloration or a brittle print. The worst case scenario would be that the resin fails to cure.
There is no harm or danger in using expired resin. The smart thing to do is to try to use it and see what happens. There are many users who report printing with resin that had expired up to two years prior to using it! Our advice is to go for it before you do anything else. But what if it does not cure or it produces poor prints?
How To Safely Dispose of Expired Resin ?
Liquid resin is six times more toxic than filament. It requires safe handling. Generally, you want to avoid touching it with your bare hands by wearing gloves as it is irritating to the skin. You also want to wear a face mask to avoid inhaling it. You also do not want to swallow it or let it get into your eyes.
Resin is also particularly harmful to the environment so you want to be careful how you dispose of it. Avoid letting your resin expire by using your oldest resins first.
The best way to dispose of resin is to cure it. This makes it much less toxic and is a far better solution than simply pouring it down your drain. All you need to do to cure your expired resin is put it out in the sun. Then you can safely throw it out. Resin that cannot be cured should be taken to a waste recycling plant.
How Long Can Resin Sit In A 3D Printer?
Resin can be left to sit in a printer vat for up to 2 months. The most important factor is to ensure the resin is exposed to as little light as possible. Most resin printers will have a UV-proof lid for closing the vat and preventing light from filtering through. A dark room goes a long way in making double sure the resin does not harden while in the vat.
In this case you should treat your vat almost like you would a container. Keep it closed, under cool temperatures and away from direct sunlight.