How often do you actually regenerate your desiccant?

Bambu Filament and Accesories
41

Gotcha, and real world experience is useful. But your experience is not typical and others seeing what you do with desiccant and that you get acceptable results could have left thinking they could treat their filament the same way.

You didn’t say anything about your ambient conditions until you elaborated, though. Your unique conditions are important to state when telling others how you use silica gel because your technique is not optimal and is how others in higher humidity environments can cause problems for themselves.

You are luckily in a dry enough ambient environment that how you use silica gel doesn’t matter but I still say you would be better off ripping out all the desiccant you are using. Since you are still drying your filament, your dryer will perform better without the added water load.

But it’s your unique environment that lets you escape consequences of how you are using beads.

42

Thanks for setting me straight. Don’t know if I could have made it through the day without your Godly insight! I didn’t know you were a Bambu Lab owner, I will send all coupons your way.

“Scotty - Beam me up! No intelligent, peaceful life here”
" SNIP! "

43

Dude, I wasn’t setting you straight. You popped in telling everyone how you use silica gel beads wrong and how you get great prints - implying anyone doing things more carefully/properly is doing it wrong. You left off all the details that explain why you are able to get away with doing things wrong.

All I was doing was pointing out your methods are problematic so others don’t waste their time and money with wasted prints because of your “testimonial”. You think bad information should be allowed to stand unchallenged just because it was you that posted it? Really?

That’s the problem when you post bad advice – somebody might try to correct it so you don’t cause troubles for others.

If you think anything I said about drying is wrong, correct me. In the mean time, sorry you got offended. I tried to explain the why but obviously you don’t care about the why.

44

It is, but it requires testing to find the sweet spot. Please feel free to share any information you have about drying times.

45

That’s also what I’m worried about with silica or molecular sieve, even if it’s not caused by friction some of the beads will likely crack while drying and form small particles or dust. I started thinking about designing desiccant holders into which replaceable pieces of coffee filter could be inserted to prevent dust from falling out, but I don’t even know if that would be a good idea. Maybe it’s just easier to use a vacuum cleaner every time you replace the desiccant?

46

Some of the most prolific posters on this forum regularly post information that doesn’t square with reality and then question the intelligence, often rather rudely, of those who point out the errors. Which inspires the yokels to jump in like jackals at a feeding frenzy. It is a quality about this forum that keeps people on edge.

Personally, I think that those who think that they have to regularly run their filament through a dryer are wasting time and energy. When I look up the science I see that PLA is classified as being hydrophobic - as is PETG. I have seen the graphs that have been generated by scientific measuring equipment which show that PLA soaked in water, loses most of the moisture within seconds after being removed from the water. Which is to say, that if someone dried their desiccant along with their PLA filament, that the operation would be mostly recharging the desiccant while needlessly heating the PLA. If one looks through the instruction manual for the AMS2 it seems to indicate that the desiccant packets are to remain throughout the drying operations - only to be replaced when they stop being effective.

It is easy to say that someone like Maker_Grandpa is an outlier because he lives in the great American desert, which includes parts of California, Arizona, New Mexico, Texas, Oklahoma, Colorado, Utah, Wyoming, the Dakotas, Montana, Idaho, Oregon, Washington, Nebraska and Kansas. But I live in the rain forest. Currently the outside humidity is sitting at 100% while the indoor humidity, with air filtration, tends to run around 40%. I tend to keep my filament in dry boxes but I am not strict about it and often leave a spool or two lying about unprotected. On my A1, I have left filament on the AMS Lite for months without ill effect. I never dry my filament with a dryer. I have never had moisture caused print failures.

But then, the air quality is very good around here with all the trees and abundance of flora and the fact that it is upwind of everything that pollutes, in addition to the interior air filtration. Being as dust tends to attach itself to atmospheric moisture I sometimes wonder if some people tend to get poor performance from their 3D printers because of bad air. That in a dirty air environment, reducing the humidity reduces the attached air born dust particles. Nothing like a few acid rain droplets to spice up one’s 3D printing experience.

Nitrogen is the most abundant element in the atmosphere. But it comes in packs of two nitrogen atoms which are tightly bound to each other, making the molecule highly inert. On its own, gasoline is just carbon and hydrogen. But when the sparkplugs ignite the gas in the engine cylinders, the spark has enough energy that it breaks the bonds that hold atmospheric nitrogen together - releasing nitrogen atoms which can then react with the oxygen and hydrogen components of the chemical reaction to produce nitric acid. Nitric acid breaks down PLA and other filaments. Which is to say that the cause of one’s print failure just may be a lot of traffic that day. Passing gasoline powered cars leaving behind little reminders of the damage they do to the environment.

47

I think nobody in this thread has suggested to do that?
It is all about drying the filament once and then keeping it dry, e.g. with desiccant inside any type of container and when to replace / regenerate the desiccant.

And certainly not all filaments are the same. Different PLA types seem to be very similar. In a dry environment you probably can do whatever you want and it will print very good.
With PETG it starts to become more interesting and there, variations between makes are clearly visible. Some have been treated to either absorb humidity slower or reduce effects from humidity. Others haven’t, probably to avoid the negative effects from such a treatment. Even within BambuLab’s own lineup, only PETG HF had the explicit instruction to dry it before use. I have also seen very different susceptibility from different brands. The first time I tried PETG, that brand really sizzled and steamed from the nozzle. Very impressive experience and I had no idea at the time.

I would be really interested to see that. It is the first time I hear about PETG as hydrophobic. Printed parts are resistant to water, maybe that is what you read? But that does not say, it doesn’t absorb water, just that it doesn’t take damage from it.

You say that you are in a humid environment With an indoor humidity of 40% I would actually call that at the dry side for a printing environment.

And I assume that you have never tried any of the more hygroscopic filaments like PC or PA? Drying and keeping them dry is just no questions with those, no matter the environment.

48

Indeed, you are correct in that PETG can be both hydrophobic and hygroscopic, something that confuses many people new to the subject .

I have seen a lot of people incorrectly take the hydrophobic part as an argument that it’s not hygroscopic for some reason.

49

Since you preface your reply to me with this, I assume you think what I post “doesn’t square with reality” and that I rudely pointed out @Maker_Grandpa’s “errors”? Sorry you think I was rude and maybe I was. It’s hard to set/judge tone in these forums. But oh well. You’ll probably think my reply to you is rude too as I correct your “errors”. I apologize in advance.

I think this is the crux of your post and not sure why the other stuff was even necessary, but…

It doesn’t matter that you live in a rain forest unless you store your filament outside. What matters is your humidity where you do store your filament. Even the 40% ambient inside doesn’t matter so much since you say you store your filament in dryboxes. You give no details other than allowing you aren’t rigorous about it. You also say you don’t have moisture failures and your prints are great. That’s wonderful but tells us nothing at all concrete to judge the reality behind your statements.

And let’s examine your statements about PLA and PETG. You claim both are hydrophobic and give up their water within “seconds” after being removed from water but give no citations. I can tell you why. That isn’t true and anyone who has dried filament knows it from personal experience - especially if they use a scale and measure/plot the water weight loss. Water loss happens over hours - not seconds - and it takes heat to do it faster and more thoroughly. You can easily verify it yourself.

What you must be talking about is if you dunk a spool in water and take it back out - yes, the water runs off and doesn’t soak in - at least that you can see with the naked eye. A person here (@recode) did that experiment. (Experimenting With Soaking Filament In Water - #23 by recode)

But if you read what recode did and observed, the filament did absorb water and it absorbed enough to fracture the polymer chains. The filament broke into pieces from the water wedging itself into the plastic. How could water have done that if the filament was “hydrophobic”? It actually is somewhat “hydrophobic” but there are also additives and dyes in there too. And lots of surface pits and cracks that expose lots of hydrophilic sites. It can adsorb enough water to hear hissing and popping as it turns to steam in the extruder.

PLA is polylactic acid and PETG is polyethylene terephthalate glycol. Those are not that hydrophobic. Long chain hydrocarbons are hydrophobic. But PLA and PETG have lots of polar functional groups as parts of their structures. Those bits are hydrophilic (water-loving).

It is incorrect to say that PLA and PETG filament is unqualified hydrophobic and all the water leaves in seconds. You can easily - easily - verify this yourself using a fairly cheap scale and heat source.

You call your storage “dry boxes” but give no details. Not only did we have a person here post about how time in an AMS (I) with fresh desiccant made filament that had started showing water effects behave again, but there are now video reviews of the Sunlu i10 dehydrating cabinet removing enough water from filament that print quality on overhang, stringing, and other tests noticeably improved.

Without details we don’t know if your dryboxes are silently helping you or not but I’d guess if you are keeping desiccant fresh in them that they are. And it takes a while for most filaments to absorb much water out of the air. You can let a spool sit out for a while without it picking up much water.

And what you call fine/great may be different from what I do.

About regular and repeated drying being a waste of time and energy, I would agree. Store filament properly and you rarely have to re-dry it.

Likewise you said “Which is to say, that if someone dried their desiccant along with their PLA filament, that the operation would be mostly recharging the desiccant while needlessly heating the PLA.” and I mostly agree. I said separate them in the post Grandpa replied to. I said he would do much better to dry them separately however, which gives up more water is hard to say. There’s a number of factors involved.

Thing is drying filament is complex and there’s much more going on than you can see with the naked eye. Filament does have desiccant behaviors but is a weak desiccant. It does adsorb water. And that water doesn’t just fall off. It’s hard to remove.

Not everyone has the same conditions. Not everyone dries or stores their filament the same way. And many don’y fully understand the subtleties of filament drying. There’s nothing wrong with posting personal experiences. But yours really gave no useful information to guide others. You lead off with how you live in a rainforest but that and room humidity don’t matter with dryboxes. What matters is the humidity in them. And how long you leave what kind of filament out and exposed. Would be nice to actually have spool humidity values too.

50

Nobody should hold their breath. That news won’t be breaking ever.

51

The first part was an explanation of why the other poster reacted as he did. He was telling us what was working for him and you dismissed him as if his experience didn’t matter. That somehow he was wrong.

The thing about 3D printers, especially the Bambu Lab 3D printers is that they are incredibly easy to use. Especially so with PLA. There are pubescent children who can operate them with ease. It is not rocket science. From my point of view I can spend my time and energy working on a design, confident that my printers will faithfully produce whatever I design 99% of the time.

When I first got a 3D printer, I would go on line to read what others were saying and would watch videos. As I began to understand my printer I began to realize that most of the experts tended to be noodlers looking for followers to entertain. The first crack came over the use of IPA. Seemingly everyone associated with 3D printing insisted that one had to religiously clean their build plates with IPA. Early on I came to realize that IPA was not my friend. I even did an experiment where I would wipe down half the plate with IPA and the other half with just a dry cloth. The dry cloth clearly won that battle time and again. By then, the use of IPA had become gospel among the 3D community and any mention questioning its use was treated as if it was heresy. I recently got an X2D. I took the Bambu Academy lessons on the X2D. On the section explaining the cleaning of build plates they specifically warned against using IPA, even showing a diagram on how IPA fails to clean the plates, and makes them worse. It made me think of the clowns who called me such derogatory terms for pointing out that reality.

The 3D printing orthodoxy keeps telling us how susceptible PLA is to hydrophilic forces. Yet when I go to material science sources I find that PLA is hydrophobic. The orthodoxy likes to tout an experiment that appears to show PLA being degraded after having been submerged under water for a length of time. In my world, PLA does not degrade in water. I have water guns and little water pumps with water tanks to hold a supply of water. The pottery that my plants reside are 3D printed PLA. All these devices are in constant contact with water and no degradation can be seen. It is because PLA does not chemically react with water. The moisture on PLA is on the surface, not in the PLA. However, there are acidic solutions that will eat PLA and other plastics.

I originally kept my rolls of unused filament in IKEA boxes. Mostly just to keep them organized, eight to a box. I bought some cheap hygrometers and some Dry & Dry desiccant packets. Threw a few packets in each container. The hygrometers would vary between 15 and 20%. I also put a couple of desiccant packets in the AMS unit. When the dry indicator on the AMS unit would get to C I would recharge the desiccant all around, in the microwave. Then I upgraded my boxes to smaller more manageable ones with seals. I went a little crazy ensuring that all the hygrometers were always at their lowest settings. But then I inadvertently left a lid off one of the boxes. When I put the lid back on, the hygrometer read 30%. I wanted to use one the filaments in that box so I loaded it up and it printed without issue. It got me thinking, if when I kept my filament around 15-20% humidity they printed fine, and if they printed fine at 10% and again after having been left out at 30% they printed fine, did the humidity matter that much. Which of course leads to the idea that PLA is very forgiving and allows a wide variety of practices, as to its use and care.

I have spent enough time in underground electronic labs and in clean rooms to be well aware that environmental contamination, including dust, can cause a lot of problems. Keeping one’s filament in sealed containers prevents that contamination.

52

Scene: A laboratory in ancient rome

“Clearly,” said Cassianus, “the invisible humour in the air and our provisions is driven out by heat, for the stones tell us so.”
“Absurd,” replied Varro, “sand absorbs it, and my magical beans prove the matter beyond dispute.”
“You have merely taught the rocks to change their weight,” said Cassianus. “Neither of us can sense the essence itself, so we are arguing over shadows cast by a thing neither man can perceive.”
“Then perhaps,” said Varro, “the true scientific instrument is humility, though I fear Rome has manufactured rather fewer of those than beans.”
“Nonsense,” said Cassianus, “your beans are obviously defective, and I shall prove it by heating them until they become rocks.”

If the romans only had that Sunlu dry cabinet

53

Think there are some mixing of terms. Example, hydrophobic is not the opposite of hygroscopic. Hydrophobic relates to surface wetting and hygroscopic is vapor sorption. PLA’s chemistry hydrogen-bonds water in the amorphous phase. PLA is not strongly hydrophobic. “Loses moisture in seconds” refers to the surface water. Absorbed water leaves by diffusion which takes days at room temperature (a dry box) and hours at drying temperature (source is MyTechFun). Saying that PLA doesn’t react with water is not true. PLA degrades through the hydrolysis of its esters. It’s slow below the glass transition temp which why planters etc survive. However in the melt zone, this reaction is fast which is why it affects viscosity (strings and oozes) while the steam causes bubbles and subsequently zits.

It is correct though that PLA moisture update is small, something like 0.2-0.3% at 50% RH and it maxes out at around 1% versus 2.5-3% for PA6. Visible print effects at moderate RH should be minor. I guess the question then becomes: “How much degadation is tolerable?” I don’t store PLA in dry boxes nor to I automatically pop it in the dryer before a print. Depends on how long it’s been sitting in my closet.

PETG shows the effects more because it’s printed at a higher temperature. Even more so with PCTG. That’s why I keep them in dry boxes and for critical prints pop them in the dryer before hand.

One area that people tend to overlook is additives. It matters a lot what is added to the polymer by the vendor. Things like wood, cellulose, TPU impact modifiers will raise moisture uptake. High mineral loadings in (for example) matte filaments will also increase uptake.

As for which desiccant I use? Mostly activated alumina with a hygrometer. I recharge it in a convection oven at 250° for 2 hrs when the hygrometer starts to climb above 20%. If I’m feeling lazy I replace it with fresh.

54

Hey, I just bag up the used silica and put on cooking paper in the oven immediately after I’ve finished cooking, the oven is switched off but the residual heat turns the beads back to bright orange within an hour sometimes less, then quickly pop back into a fresh freezer back, seal and reuse when needed

55

So if someone is wrong we are not supposed to point that out now? Grandpa was leaving important details out which gave the wrong impression to others. His ambient environment, while not super dry, is adequate to get prints out especially if he has tuned out some water effects. He’s close to the edge but he gets away with poor drying techniques.

Your post was largely just wrong with what you said about water absorption and hydrophobicity.

I don’t know what you want me to do here. I tried to be nice to Grandpa and used lots of wiggle words, but his advice was bad. He made out like he didn’t need to dry so others don’t either - which is flat out wrong. You implied the same thing and laid it all out again.

Go back and read my reply to Grandpa. I didn’t dismiss his experience as not mattering. On the contrary. I said it was important to include all the details which others can use to see if his experience applies to them.

You have a room dry enough to store and print with that doesn’t require you to dry. That’s great. But my ambient was hitting 40% and I was seeing water effects - effects that went away once I was drying effectively. Relative humidity does matter. It may not to you but it does to other people.

That’s the whole deal, Ed. All your numbers are 30% or below. My personal threshold on PLA is 25% and even then I see water effects until I get below 20%. You are in the ballpark. You apparently don’t need to dry and good for you.

So you tell me. You come in here and proclaim you live in a rainforest and don’t have to dry your filament. You say you leave filament out in the open, again implying you’re in a humid environment and you can treat PLA just any old way. You now give 30% as your high humidity when in your reply to me you said your room was 40%. Whatever.

The thing is it’s good to have people post the real information, not hidden in prose about rainforests, flower pots, and room humidity when you use dryboxes. That’s what piqued my interest in your post to me - you belabored how wet everything was and yet you didn’t need to dry. That’s deceptive. That’s why I mentioned actual humidity.

And your discussion of hydrophobic/hydrophilic isn’t based in reality. You also apparently don’t appreciate the difference between injection-molded polystyrene and something called polylactic acid. You also don’t appreciate surface morphology, cracks, pits, and fissures. All this stuff matters.

Have you looked at a micrograph of filament? Filament is extruded to manufacture it. Some think that filament should be just like the things we print. It’s not. Extruded filament is being cooled so it holds diameter and doesn’t just drip out of the extruder used in production. It’s done fast. That leads to a very different surface than when molten filament is extruded for a print and cools in place. Things printed with filament get much smoother surfaces so water can’t attack it the same as the rough surface of a filament strand.

And you are also just wrong about PLA not reacting with water. It does. It’s a slow process when the surface is smooth because the surface area is way lower. The PLA undergoes a hydrolysis reaction. It is a real, honest to god chemical reaction that changes the PLA. It attacks the ester functionality and breaks the polymer into individual lactic acid monomer molecules. That is a chemical reaction.

But again, this isn’t a reaction you can easily see with your Mk I eyeballs. The molecules’ sizes are measured in nanometers and smaller. You can’t see it but it is there and it is happening - flower pots or no. PLA will degrade in water. Another experiment you can do yourself just like recode did.

You could also have looked all this stuff up for yourself. Instead you post like you know all about this stuff except you actually don’t. Look up hydrolysis of PLA. Look up micrographs of filament strands and learn the differences between polystyrene and PLA/PETG. And learn about reaction rates. Dunking something in water for a minute is very different from submersing it for days or months. Time does have a toll. A much smoother surface will greatly extend how long things can be exposed to water compared with rough surfaces.

Anyway, whatever. It’s not fair to other people here to post about 100% humidity in a rainforest and how you don’t have to dry your filament when a little prodding and we find out your conditions are actually pretty dry. That’s why you don’t need to dry filament. Not because PLA is so forgiving. You were embellishing your story to make it sound better and so made it deceptive.

I guess we aren’t supposed to call that out now.

56

I’ll chime in. Stating that something is hydrophilic or hydrophobic is a little misleading unless that substance is chemically or molecularly pure. I don’t know all of the other chemicals or their concentrations that make up a spool of PLA and I would imagine that varies with color and manufacture.

Nevertheless, PLA is less susceptible to water absorption and does not require the care that filaments such as nylon do. It also seems that repeated drying of PLA is not only bad for your electric bill, but possibly degrades the filament. I can’t imagine drying PLA and storing it in a low humidity container is a bad idea.

I don’t like drying filament, but that is because it takes time to do it and delays printing, so I tend to try to keep filament in dry containers.

To answer the original question, I only regenerate desiccant when I have a large enough batch worth firing up my blast oven. I bought a large container of 4A molecular sieve almost 2 years ago and I have used a little more than half of the container to date. The rest is waiting in plastic bags to be regenerated, but even my blast oven can’t reach the published region temperatures. Molecular sieve has greatly extended the intervals required for regeneration compared to silica gel. Even if I can’t regenerate molecular sieve I would just buy another jug of the stuff at the rate I go through it. Works out to less than $25 a year.

57

You do a great job highlighting the core of such discussions. :+1:

What often gets lost or is left out, is the missing context that completely changes the meaning of a statement.

To give a rough idea so I’m not pointing fingers at anyone:

If someone say, “I never dry my filament, even when it’s humid outside!” it sounds misleading. What it can really mean is: “My workshop stays dry, and I use filament quickly enough that moisture isn’t an issue. It doesn’t matter what the weather is like outside.”

In short: a rainforest can have a dry workshop, and a desert can have a humid one. That’s why these statements only make sense when the context is included - otherwise people can easily misunderstand them or take away the opposite impression.

58

That’s not really the case for me. I pay about 10.5 cents per kWh here in Florida, so regenerating the silica gel costs very little. I avoid overheating it, and I’ve reused the same beads many times. I’ve also tested them after multiple regeneration cycles, and they continue to absorb moisture just fine. For me, throwing them away and buying new ones every time would make much less sense. :money_mouth_face:

59

That’s it right there. Personal experiences can help give others insight into their own filament issues but it stops being helpful if people are inaccurate in describing the circumstances.

What matters when describing having to dry or not is what humidity the filament is actually exposed to. The outside humidity only matters if that’s where the filament is stored. It can also be central to discussing how to overcome high humidity as in “I live in a rainforest and have to use dryboxes to keep filament moisture down” or “my A/C keeps humidity low enough”. But implying they don’t dry even in high humidity environments and everything is great doesn’t actually help anyone troubleshoot their own issues. It’s misleading. Added - and not saying it’s intentional.

And for all the people who don’t need to dry, when highlighting your successes about not drying, it would really help if you include photos of prints actually printed from your undried filament. There are subtle issues that appear as moisture content increases and we need to be able to judge the print quality for ourselves.