We get a lot of questions about the perfect humidity levels for different types of filament. There’s a lot of opinions circulating about what room humidity level is best, what is just okay, and what is unacceptable.
When it comes to the perfect humidity level, the truth is… we don’t know exactly.
There are not currently any hard and fast rules. There is no magic number that will give you perfectly printed objects. Even manufacturers of filaments don't have recommnded humidity levels posted in their product descriptions. But you do know firsthand that every roll of filament you have ever bought has come with a desiccant pack, and likely it was also vacuum sealed. The manufacturers know humidity is a problem, but the specifics are lacking.
We know that some filaments are more sensitive to moisture in the air. Some filaments can be stored in the open, depending on the climate in your area. While there are some tried and true ways to protect your filament, optimal humidity levels can only be found through some good old fashioned trial and error.
Here’s what we know:
PLA (POLYLACTIC ACID)
PLA holds up fairly well against humidity. Below 50% room humidity usually yields good results during production. Anything higher will risk air pockets, brittle construction, and a dull appearance.
50% humidity is pretty common in most households. Because of this, some people don’t have problems storing PLA in the open air without any dehumidifiers or storage containers. However, even if the air in your home is typically pretty dry, it is still a good idea to use a filament storage container to protect from excess humidity on rainy days as well as accumulation of dust, pet hair, or other contaminants.
ABS (ACRYLONITRILE BUTADIENE STYRENE)
ABS is even more resilient to humidity than PLA. Out of all of the common 3D printing filaments, it is affected the least by ambient humidity. Even 65-70% humidity has been found to yield good results during production for some people.
Again, even if your house stays under these humidity levels typically, it is still worthwhile to store it in a protective case. One or two surprisingly humid days can affect your entire stock of filament. This would only create more work for you in the long run as you either spend hours drying out your filament in the oven or shell out the money to buy special filament drying appliances or new filament altogether.
PETG (POLYETHYLENE TEREPHTHALATE GLYCOL)
PETG is more of a concern than PLA or ABS. It needs to be kept at a humidity level well below 50%. If you are storing at 50% humidity, you may get small blisters and a dull appearance with production. It seems that a humidity level of 20% or less will yield best results with PETG.
This is where a decent storage container really becomes your best friend. You’re not going to be able to leave a spool of PETG out for an extended period of time without seeing some serious negative effects the next time you try to print something. Purchasing a storage container will save you time and save you money as you will not be wasting filament on misshaped, sloppy projects.
Nylon is the most difficult to store. It is incredibly hygroscopic. So much so, that some people put it in the oven to dry it out before every use, just to be safe. Even people who store it say that the storage really only helps for a short period of time.
At 10% humidity, nylon will still absorb enough water from the air to cause problems in production. Try to store nylon at as low of a humidity level as you possibly can. Some forums suggest 3% or less, if possible.
THE BOTTOM LINE
Ultimately, you are not going to hurt your filament by storing at lower humidity. For all of the above-listed filaments, the lower the humidity levels, the better. If you live in a very humid area or in an area that has drastic changes in humidity throughout the year, you really should be protecting your product. Unless you want to spend hours drying out spools of filament in your oven, it’s best to keep humidity levels as low as possible in your storage container.
You may find that the area you live in is already dry enough and you feel that you don’t need to go out of your way to create a controlled storage bin for your filament. Even in this case, you can still benefit from a good storage container. You invest a decent amount of money in these spools. If you only have a rainy day here and there that puts your humidity up over optimal levels, you will have the peace of mind knowing that your materials are protected and you don’t have to scramble to piece together a protective container. It will also protect your spools from dust, accidental spills, or other contaminants.
The 3D printer filament storage container by Katamco is the most economical and efficient method of keeping filament protected. And it comes with premium desiccant that is easily and safely rechargeable in your microwave.
What is the Optimal Humidity Level for 3D Printer Filament? Our Official Answer: As low as you can get it.