Filament storage bags

[mawyatt]

Reason for question arrises from some limited knowledge about humidity. A little story behind this, a former professor colleague moved to Northern Arizona University for medical reasons. We visited him and met many of his graduate students and they were working with a NSF grant to study forestry effects and had developed remote devices for collecting data that were attached to trees. They were failing in the field due to humidity effects but were in "sealed" plastic boxes, altho a couple failed because bears liked to chew on them

When the data was presented we immediately knew why they were having problems. Told them to drill a small hole in the bottom of the box to allow it to breath and place a Gortex fabric over the hole to keep insects out. Gortex allows breathing but prevents liquid water from flowing. Water molecules are smaller than the general atmosphere made up of mostly Nitrogen, but as N2, so unless something is truly hermetically sealed water molecules may enter as they are smaller than N2. Allowing this breathing by means of the Gortex fabric will keep the internal dynamic humidity lower than sealing the box where the water molecules enter but don't leave during the large temperature excursions the box experiences in the forest environment and condensation takes place and affects the electronics. They followed our advise and had no more condensation problems, altho the bears still like to chew them up

So question is, do the vacuum bags for filament actually work as well as one might think? Seems possible that water molecules would be drawn in by the lower internal bag pressure and build up in the sealed bag. The desiccant will of course absorb the small amount of intruding water molecules and keep the humidity low and this works well for the factory sealed bags which start with new desiccant. However, it seems that if a vacuum bag is used with a weak desiccant that over a long term and with some temperature extrusions the internal humidity could be higher than if the bag were just at normal pressure and not at a lower pressure to help draw in the water molecules??

Since starting 3D printing a few years ago we've accumulated some "open" filament, mostly PLA and we are in Florida USA where humidity is a constant problem. We've stored opened filament in large plastic boxes with bags of desiccant, lately been putting the open filament in Zip-Loc bags with desiccant, then into large plastic box. We are relatively new to 3D printing, have little long term experience with filament humidity effects, not sure if our method of short term storage is effective and considering the vacuum bags.

What are others experience with vacuum bags??

Best,

[Jeroen3]

I toss the bags, they're annoying. But if it's all you have.
When properly vacuum sealed they work, because if moisture goes in, the vacuum has failed.
The little silica pouch is for transport. It's very poor at absorbing moisture.
Re-zipping the bag with the pouch is better than nothing, because the filament itself is hygroscopic itself it will limit the amount of moisture to that what's in the bag. Meaning it will not get any more worse.
The bag will not breathe because it will move with pressure changes, the problem with the hard plastic bins in temperature and pressure changes is that the box does not breathe. Hence the need for the breathing hole or it will find a way!

Now, I drove to Ikea and got a few of the largest SAMLA bins to stack spools in. Add a chemical dehumidifier, which lasts years because the box volume is small and the absolute humidity can't be very big. And I have storage for filaments. The problem is this storage is finite and filament mulitplies...
This keeps spools in dry atmosphere, available at hand, without hassle of the bags. It not an indefinite solution, but filament is a consumable. At least it should be.

If I need a high quality print an doubt the filament I put it in the dryer for a few hours.

If you're in a significant humid climate you can take a look at the guidelines for moisture sensitive electronics parts, maybe even add those little "bake before use" cards. 
The Pick and Place podcast have an episode on this.

[mawyatt]

Thanks for the information. The IKEA SAMLA boxes are really good, been using them for all sorts of storage, electronics and otherwise for many years now. They've held up well over time, without becoming brittle nor yellowing, good value!!

Best,

[jpanhalt]

In our microbiology lab, we chose tape for keeping petri dishes securely closed based on permeability to various gasses -- namely CO2 and O2.  I no longer have that data, but this link may help: https://www.hindawi.com/journals/ijps/2012/302029/

In brief, many thin polymer films are permeable to various gases, including water vapor.  The mere fact that filament absorbs it is indirect evidence of that.

Glass and thicker plastic is safe so far as I know.  Thus, a large glass dessicator may suffice and be even better with a light vacuum applied.  If you use a vacuum, be aware of the dangers.  Using a drier (e.g., Drierite, calcium sulfate) is safer.

[BlackICE]

How about mylar vacuum bags?

[TomKatt]

I don't know if there are different quality bags on Amazon, but the ones I tried never held a vacuum for more than a few days.  I don't have much faith in those Ziplock style bags for longer term storage.

I recently got the PrintDry Vacuum Storage container and have been very impressed with it - very easy to use and it has a vacuum pressure sensor that will automatically turn on the pump if it detects the vacuum has decreased.  The rechargeable batteries claim to hold a charge for months and the container holds (3) 1kg spools.  A little pricey at $100 but worth the money spent on pricier filaments that are moisture sensitive.

I keep my PLA in my Bambu AMS unit and printed some additional Dessicant bead holders that fit inside - the AMS lid has a nice rubber gasket seal and the desiccant is over 6 months old and still indicating the lowest humidity level.

Finally, I have an Eibos Polyphemus filament dryer that has a storage mode and keeps 2 spools at around 10% - it will automatically turn on low heat and fan just enough to keep the filament dry without using as much power as the actual drying mode uses.  It's also the only filament dryer I've found so far that automatically rotates the spools while drying so the filament is evenly heated.

All in all this gear provides dry storage for (9) 1Kg spools.

[CatalinaWOW]

Of course those vacuum bags won't keep things dry forever.  Nothing short of metal boxes with metal to metal seals will.  But they are better than purely open storage.  So far I haven't found them to be enough better to be worth the hassle.

I have found wet filament pretty easy to detect, and easy to dry, so in my not particularly challenging environment I just store open.  The other piece of that is not keeping huge stocks of filament on hand.  I usually only have a couple of types in a couple of basic colors, with backup for only my two most commonly used.

[wraper]

Transparent bags do not stop moisture regardless if there is a lowered air pressure inside (which you call vacuum) or not. They're pretty much useless to keep filament dry with a tiny pouch of desiccant they come with. The real thing are moisture barrier bags with aluminum layer. EDIT: wrong datasheet https://www.descoindustries.com/PDF/Dri-Shield-3400-Moisture-Barrier-Bag.pdf When marketed for storing food, they're called mylar bags for some stupid reason.
"Vaccum" is redundant, that's why usually electronic components that come in these bags don't have air pumped out.

[TomKatt]

Transparent bags do not stop moisture regardless if there is a lowered air pressure inside (which you call vacuum) or not. They're pretty much useless to keep filament dry with a tiny pouch of desiccant they come with. The real thing are moisture barrier bags with aluminum layer. https://www.descoindustries.com/PDF/81705-Bags.pdf When marketed for storing food, thy're called mylar bags for some stupid reason.
"Vaccum" is redundant, that's why usually electronic components that come in these bags don't have air pumped out.

Those look like they need to be heat sealed?

[wraper]

Transparent bags do not stop moisture regardless if there is a lowered air pressure inside (which you call vacuum) or not. They're pretty much useless to keep filament dry with a tiny pouch of desiccant they come with. The real thing are moisture barrier bags with aluminum layer. https://www.descoindustries.com/PDF/81705-Bags.pdf When marketed for storing food, thy're called mylar bags for some stupid reason.
"Vaccum" is redundant, that's why usually electronic components that come in these bags don't have air pumped out.

Those look like they need to be heat sealed?

There are resealable bags but I don't bother with those and just roll an open end a few turns and fix it with a paper clamp. It's more airtight than resealable IME. And according to moisture indicator cards i put there, works great by keeping moisture <5% for a few years with a dried medium size silica gel pouch. Note there is a cheap version of these that uses metallization instead of metal film, they have about 10x more moisture penetration. Still will run circles around regular transparent bags though. And obviously you need to dry the filament first, PETG, ABS and especially Nylon are nearly always wet as received in factory package. Even when filament comes in a moisture barrier bag, often it's wet anyway.

[wraper]

[lilshawn]

has anyone used those chemical desiccant containers that turn from spherical beads to a goopy liquid when depleted like pic related...? (they are apparently Calcium Chloride)  I can obtain these pretty cheap (2 or 3$ each) or do they maybe not remove enough moisture to be of use? having a visual indicator of depletion without futzing around with baking silica gel to dry it is appealing to me.

[jpanhalt]

Calcium chloride is cheap for a reason.  It is one-time use, makes a goo, and cannot be regenerated by any method you might want to use.  Use a sulfate-based drier, silica gel, or molecular sieve that are easily regenerated.

[lilshawn]

fair enough. I've been using large silica gel packs in some super heavy duty zipseal bags. (bags are made out of made out of 1 mm thick plastic) i also have digital hygrometers in the bags to keep an eye on the humidity levels, but haven't been able to get great stable humidity levels. the silica gel seems to take a LOOONG time to adsorb any humidity that ends up in there from just opening the bag. I've dried the desiccant several times, but it just doesn't seem to be able to cope with even just opening the bag to pull a reel out without taking days to get back to where it was.

was just going to see if maybe switching up the desiccant would help.

[jpanhalt]

Have you consider a vacuum desiccator and vacuum pump?  There's not much humidity at 1mm Hg.

[lilshawn]

I had considered a vacuum desiccator at one time but "cheaper" ones like what you find on amazon are only rated to hold vacuum for ~24 hours at room temp... with larger lab quality cabinets rated to hold 72 hours... and i'd be looking at 3000 bucks for one of those... and it would hold probably three 1kg spools of filament...4 tops. and with the number of spools i have at this point I'd need 8 or 9 of them.

I mean, I don't mind throwing away money, but I'll be long dead before I throw away 25k worth of those Calcium Chloride moisture absorbers at a couple bucks a piece. (which is why I asked if anyone has ever used or considered using them)

If they are capable of removing enough moisture from the air, in a sealed bag or even a moderately sealed plastic box, i think they would last a pretty long time. i just don't know how low they can go.

maybe an experiment is in order.

[wraper]

You probably don't want to store filament at anything close to a real vacuum as you don't know the effects filament outgassing will cause.

[jpanhalt]

I have a couple of glass vacuum desiccators collected over the years (attachment).  I had no idea the price was so high today.  Plastic ones are cheaper (less than 10%), but I did not see what their ratings for retention were.  My high-vac pumps are also dumpster finds.  One would not need a high vacuum.  Vapor pressure of water at 0°C is 4.6 mm Hg.  Buying new would probably be prohibitively expensive.

As for the effects (good or bad) of outgassed filament, I don't know.  My understanding was that outgassing water vapor during heating was what causes the problems.  I searched on that and found a link to an interesting table created by NASA: https://outgassing.nasa.gov/

My apologies for suggesting something that may be off the wall.  I am very new to 3D and filament printing.  My background dealing with humidity- and oxygen-sensitive stuff comes from chemistry.

[wraper]

As for the effects (good or bad) of outgassed filament, I don't know.  My understanding was that outgassing water vapor during heating was what causes the problems.  I searched on that and found a link to an interesting table created by NASA: https://outgassing.nasa.gov/

If it would lose just water it would be fine, it's what you want to begin with when drying filament. However it's not water only, filament may lose plasticizers or whatever may be in there.

[tggzzz]

I have zero knowledge of drying filament, but I know very cheap "food dehydrators" are effective at removing moisture from mushrooms, mooli, etc. They work by reducing the relative humidity by heating air and blowing it past the sliced food. The air temperature can be set to be low (35/40C), so I guess that wouldn't affect the filament.

If nothing else, it would be a cheap, fast, and simple experiment to see whether increased humidity is affecting the filament.

Example, without recommendation, a Homcom 5 Tier Food Dehydrator

[janoc]

I have zero knowledge of drying filament, but I know very cheap "food dehydrators" are effective at removing moisture from mushrooms, mooli, etc. They work by reducing the relative humidity by heating air and blowing it past the sliced food. The air temperature can be set to be low (35/40C), so I guess that wouldn't affect the filament.

If nothing else, it would be a cheap, fast, and simple experiment to see whether increased humidity is affecting the filament.

Example, without recommendation, a Homcom 5 Tier Food Dehydrator

I have one of these dehydrators (they come under different brand names). It works quite well, both for drying filament & regenerating the silicagel. One only needs to modify the trays inside a bit to fit the filament spools. Also don't expect a tightly wound spool to be perfectly dried - the warm air won't get to the inner filament layers, so you may need to dry multiple times as the dry filament on the outside is used up.

I wouldn't bother with kitchen vacuum sealers (or the same devices sold for filament storage at a premium) - these just don't work. The cheap plastic bags may keep "vacuum" (that's far from an actual vacuum) for a while but usually won't stop moisture from getting in over time. Don't waste your money on that unless you want it to keep your veg fresh in the fridge.

I am storing my filament in large plastic boxes with a lid and a tight fitting rubber seal under it (plenty of options on Amazon), with some silicagel at the bottom. And use one of these dryers to dry the filament before use for a few hours. With filaments like Nylon you really have to dry regardless of how you stored it anyway.

[Pinkus]

I am using those:  https://www.amazon.com/gp/product/B0D477PHNZ and can recommend them.
These are leak-proof for many months and can be used several times. They are supplied with a small pump and this works well. Only the foil valves on the bags are a little tricky, i.e. you have to pump 10 times before they open - but once you know that, it's not a problem.

[wraper]

^Waste of money. For this price you can buy real moisture barrier bags and much larger pouches of silica gel which will keep filament dry for years, and will have some money left.

[Halcyon]

For what it's worth, I used to use these for storing expensive camera gear years ago: https://www.silicagel.com.au/hydrosorbent-dehumidifiers/40gm-mini-canister
They can be dried out in a normal oven (or somewhere equally hot).

You can also buy reactive cards which indicate humidity levels inside a container. https://www.silicagel.com.au/humidity-indicator-cards

[wraper]

^I'm sure they work well, however price is a total ripoff (I know it's in AUD). You can buy 250g (6.2 times larger) packet for 2x less from the same place https://www.silicagel.com.au/silica-gel-packets/tyvek-250gm-packet
And it can be dried just as well.