I’ve recently got my X1C and started stocking up on Bambu Lab filaments. They typically come in nice boxes in a vacuum sealed plastic bags and generally there are no issues with them. However something bizarre started happening with PETG Basic Transparent filament spool once I got it out of the box and exposed it to light. The bag started inflating, and keeps on inflating further, most likely due to off-gazing of VOC once the filament is exposed to light. I’ve always thought Filaments are generally inert (with exception of absorbing moisture), however this one has really puzzled me since I keep my printer at home in a vented enclosure, but can’t vent the storage for filaments and definitely don’t want to expose myself and the family to VOC.
Could anyone or better yet Bambu Lab themselves possibly explain what’s going on?
Just speculating really but I assume that no vacuum was actually present when taking the bag out of its box?
While there are countless probable causes, the simplest ones may be good starting points. I’d guess that simply no vacuum was drawn during sealing. The bag then reacts to changes in outside air pressure and heating of the air in the bag/mini-greenhouse. To check, you can put it in the fridge for a few hours.
I knew this would be the first assumption I’d receive. No, the bag was vacuum sealed when I’ve unboxed it yesterday and now it somewhat resembles an inflatable pillow. Really curious how far it could go. At present I believe there is now more pressure in the package then outside.
There should not be a “mini-greenhouse” effect inside as there is barely any air or moisture to begin with, and all this gas came out within around 24hours timeframe. It was also not exposed to direct sunlight or warm temperatures (its winter after all). There is clearly an unexpected off-gassing of this specific filament. I’ll post more photos tomorrow if the pack becomes any larger.
Ok, that is, as you state in your post-title, truly bizarre.
I have seen micrographs from different thermoplastics where VOC content was an issue. However, that required temp’s above the glass transition temperature. So way over what that spool has seen for a while.
As for water, fresh spools are not neçcessarily dry. But with saturation at 1%-1.5% for PLA and typical PETG that reservoir would need a bit of heat to be released. And show when cooling down of course.
Similarly, if the desiccant was inadvertently soaked before having been sealed in, that would be quite a significant reservoir. But it would require a bit more heat than room temp to be released. And again, it would show during subsequent cooling.
If you are truly worried about abnormal material, you may want to return the spool. If it is a bad batch, you may have trouble printing it after all.
If you want to further see what is happening, I am curious about your findings.
Yes, this all indeed looks very strange. I have now dismissed the heat being the reason as the spool sat in its box for at least few days before I’ve unpacked it and all this time temperatures remained the same. It started inflating only after the spool was exposed to the lighting in my living room which was mostly LED these days.
I’ll be definitely reaching out to Bambu support as I’m not as much concerned on the moisture in the pack as on the VOC that has inflated that bag. I just don’t want a filament that will sit in my living space and continue off-gassing into environment. It would be also curious if they did an investigation on this or if someone else could repeat the experiment.
Yes, it sounds like the best approach to get a replacement roll. It may be nothing, but as a consumer, you can not be expected to either know or judge.
From my (limited) experience with the chemical industry, it is highly competetive and as a result needs to protect its mixtures and process parameters. Which is of course where things can go wrong. If there are many returns, the material supplier may need to look at what could have been a bad batch. But I doubt that even Bambu would get details.
Looks like the seal on the bag has lost integrity somewhere, and the bag is reverting to it’s original form, albeit a bit expanded in the middle due to the spool. Can you squeeze the bag and get it to collapse again? If you squeeze it, do you hear air come out?
When you go grocery shopping and leave an empty bag at home, does it inflate all the way to the inflated state? This is not “reverting to the original form” as you’ve mentioned. Although some release of vacuum tension is possible if the integrity of the bag is compromised, its not a material under stress to inflate more than the ambient air pressure around.
So you’re saying a sealed bag with a spool of filament in the middle of it is like a grocery bag? Good to know.
It doesn’t look pressurized, or inflated as you state, to me. It looks like if you threw an orange in a ziplock bag, without sealing it.
You didn’t give it a squeeze, did you?
If it was pressurized above ambient, there wouldn’t be creases in the bag. Just sayin’.
A stiff enough bag with something in the middle of it would look exactly like what you posted. The bags are more akin to card holders than they are flimsy grocery store bags. Hence, the reversion to form.
My second post in this thread reads - It has more pressure inside then outside. Of course I squeezed it.
I can’t hold my wheels here, do some people really think others are that stupid? Like are we in a barbie forum or something you’re trying to question me on some fundamentals? The filament off-gassed under exposure to light, too bad I had to put it to use and did not care to snap a photo, but the next day it inflated even more and over the top of the spool. It also smelled somewhat sour if you’re curious.
