Humidity Control For Filament Storage - How Tight Does a Container Have to Be?  

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

They need to be airtight, or you will get slow, wetting of the filament over time.  

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

If not airtight, and with a dehumidifier running, will it overtax a dehumidifier ?

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

A hygrometer will be your best bet for confirming how well you're doing.

FWIW my Polydryer boxes need the desiccant removed and refreshed every 8 weeks or so. They give the impression they're tightly sealed but once they get to 25% RH indicated on the front I swap the desiccant out and dry that when there's enough of it to batch. I keep my other spools in storage bags inside plastic tubs that also have desiccant, seals around the top and added clamps on all sides and they have a similar cycle for renewing the desiccant that's outside the bags. The stuff in the bags I swap when I open them to print.

I can only imagine a wooden structure would be quite porous to humidity so you'd have a similar challenge where you are. I love seeing the guys on youtube who can store their filaments open on a shelf nearby. But that's simply not the climate where my printer and its supplies live.

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

I've found that I can use some types of paint or shellac or stain that will create a moisture barrier on the wood, which will help. Plus I would use caulking along any joints to reduce leakage as well.

I was thinking of keeping desiccant in the storage area, but also using an active dehumidifier to help keep it dry. Considering the humidity in this area during the summer, I figure even opening the door to get a filament spool would let in a decent amount of moisture. After a lot of thought, I've decided separate the printer compartment from the storage compartment for multiple reasons. That means 2 dehumidifiers, but I've seen a lot that aren't expensive. Also, where I'm putting the cabinet, it will be easy to run tubes from dehumidifiers that will drain off any water output to the ground outside the building. (When I've used dehumidifiers in various locations in the past, I keep forgetting to empty the trays, which means they detect a full water level and stop functioning. This way they will always drain out.)

I should have mentioned I will be including a hygrometer.

I know I can't keep humidity out completely, which is why I'll use humidifiers in both compartments. My concern is that I don't want to have to get some high end, power hungry humidifier to run 24/7 and coast a lot of money to keep going. If I can keep it dry enough with a lower cost humidifier and desiccant (knowing any desiccant will have to be changed out and recharged regularly), I think that's pretty much the best I can hope for. As I mentioned, I know just opening the storage cabinet doors will be a problem. I was hoping someone might have an idea of just how much the use of wood (as opposed to other materials) will complicate the process.

Meanwhile, I'm looking into other materials. While I'm still going to build the frame with wood, I'm looking at what I can find that's not super-expensive to use for the paneling. As I mentioned, plexiglass, which I'd like to use has gone up so much it's way too expensive, especially since I'd need really thick panes of it to keep it from cracking easily and it's still going to scratch up over time.

A small dehumidifier and a mini-fan blowing dry air into the structure might be enough to provide a tiny positive pressure which in turn should keep moist air out.

Off the wall:  printing waste - find the biggest tray that will fit your oven and remelt a few dozen failed benchies into your own, home made, recycled panels.

Cheerio,

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

Look at 'IKEA SAMLA drybox' over the internet - they are large enough to store multiple spools, so people turn them into a dry boxes for storage, for example just to keep a pool of spools together, and also use it as drybox for feeding the printer - especially MMU.

You can also use a small boxes for storing a single spools for a shorter time.

There are also some threads in the forums about dryboxes, so you just need to use search function (but be patient while waiting for the results), and you will get much more different setups people already did.

All in all you will need a device to dry the filament (or two), and devices to store it in short and long term. And about a kilogram of desiccant 🙂

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

Look for Activated Alumina for a desiccant.  Much better that silicone and can be dried at a higher temperature and capture more moisture.

I found some storage containers at Wal-Mart that have gaskets seals on the lids.  I am using them for storage with a kg of activated alumina.  Stick at 10 to 13% RH at 22 degrees.  

Going to try an experiment with a desktop dehumidifier and see if I can make a large drybox out of wood to feed my MMU.

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

A friend sent me this link, where Adam Savage (of Mythbusters fame) built a filament storage box out of wood. I don't see reports from him, later, of how well it's working, but he also has an active dehumidifier, which is what I'm going to use. (But a smaller one than his.)

I will be painting the wood and using padding on the doors so that'll make a tighter seal when they're closed. I still have to find what paint will work well for a humidity barrier.

RE:

I use both silica gel and activated alumina in my dry boxes. Why both? Because activated alumina only works well when the RH is already low. On it's own in a humid atmosphere it doesn't work as well silica gel, it is however superior once the RH is already low. Also, the silica gel has an indicator. So in my Polydryer boxes the front with the hydrometer contains silica gel and the rear compartment PolyDryer Extra Desiccant Container has the alumina. So the gel acts as a "starter" to lower the RH then the alumina takes over (more or less). 

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

Thanks for the video.  Dehumidifier lowered his RH in the box which is what I want to see.  His comment about the RH for storage is much higher than I have ever read or heard.  I guess it depends on the filament type you are storing.  I would be interested in knowing the temperature in the box at the time of his reading.  Dehumidifier may heat the box up and that will change the dew point and may not provide an accurate indication of how dry the box really is at printing temperature.  Still something that I want to test. Just ordered a new sensor for monitoring since air moisture content changes with temperature, higher temperature, lower RH but higher moisture content.

As for a paint, I would look at a paint good for a bathroom or exterior.  Both should be good water barriers.

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

Thanks for the video.  Dehumidifier lowered his RH in the box which is what I want to see.  His comment about the RH for storage is much higher than I have ever read or heard.  I guess it depends on the filament type you are storing.  I would be interested in knowing the temperature in the box at the time of his reading.  Dehumidifier may heat the box up and that will change the dew point and may not provide an accurate indication of how dry the box really is at printing temperature.  Still something that I want to test. Just ordered a new sensor for monitoring since air moisture content changes with temperature, higher temperature, lower RH but higher moisture content.

As for a paint, I would look at a paint good for a bathroom or exterior.  Both should be good water barriers.

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

Sorry for double post.  Issues with the forum.  Tried to delete but it wouldn't let me.

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

Interesting comment about using silica for high humidity.  I don't agree with your comment on activated alumina at low RH from my experiences.  I found that indicator silica was not low enough when I measure RH.  It was indicating that it was ready for recharging at a point much higher than what I could print with some filaments.

My experience is related to living in a dry area and today, my air to air heat exchanger was showing a RH of 5%.  Not sure what temperature it was at though.  My room indicator was at 21% at 21 degrees.  I am about to setup a single board computer to measure the RH and temp too calculate the dew point to then give me a relative RH for 20 degrees, so I don't have to keep calculating the differences.  I want remote access for this information.  For indicator silica, I have seen it stay the same colour, even when left open for a week in our area since many are rated for 20% RH.

FWIW, I bought some cheap indicators that had an error of over 10% RH reading when tested against a couple of reference indicators.  Waste of money.  

If the indicators I am using now are accurate, there are days that I can open up my dry boxes since RH in the workshop is lower than they are indicating.  This is why I want an accurate method of measuring dew point, since that is the best way to know if the air is dry enough.

I now store all my filament in my boxes with about 1.5kg of activated alumina for 10 rolls.  Indicators are at 10 to 15% at 21-22 degrees.

For my desiccant, I use soup infusers to hold it.  They are stainless steel and can be thrown in the oven when I dry my desiccant out.  I made the mistake and got large ones.  Going to replace with smaller ones, ones that will fit in the spools, in the future, since they have better air flow for usage and drying.  I tried printed ones but that just added work of having to remove the desiccant from them before recharging.

For drying, I measure the mass of the desiccant and container before putting in the oven and then measure the mass after it has cooled.  This gives me some information of how much water was captured.

Depending on what you are printing with, the dryer the filament is, the better.  I found that that with TPU, I had to print with a drybox, even though it is dry here.  Long prints with TPU, just failed before using a dry box.  I bought a dryer for using the TPU, due to time but with proper storage, I hardly ever use my dryer.  All my filament is now in dry storage.  

I have purchased and opened vacuum packed filament, and found that when I put it in its own dry box, the RH shot up.   New filament in the bag, is NOT dry in many cases and users need to assume that they need to dry it before use.

Sorry for the winded rant.

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

Cheap hydrometers bottom out at 10% RH. 

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

Hi,

Throwing in my thoughts or solution/workflow for filament storage:

"Thoughts":
From my point of view is keeping many spools in one container made of whatever material not an optimal solution. Everytime you open the container and take out or put in a spool/spools their is also an exchange of air within the container. Yes, drying desiccant will handle this but get saturated earlier. 

"Solution/workflow" (at least at the moment, still learning...)

• unpacking the spool from manufacturer packinging when I know I will need it the next day/days
• drying the spool in a dryer (I have SpacePi X4)
  • temperature at level given from manufacturer or at a save level (keep max temperature for the roll itself in mind!)
  • drying time: I settled at min. 6 hrs, even not longer like 12 hrs for TPU or more depending on experience/feeling)
• after drying and I don't need the spool immediately - meaning for printing - I put the spool in a vacuum bag
  •  i didn't buy the cheapest bags, bought pump and bag of brand "vacloong" at Amazon
• when I need the spool:
  • -> PLA: I put the spool on the spool holder of my C1L; PLA is not humidity "sensitive" like other polymers
  • -> other than PLA: I put the spool in the dryer, set at least 45°C and print out of the dryer

From my point of view the biggest advantage of such vacuum bags is, you see it when air is coming into the bag. Yes, you have to close it carefully by following given instructions and yes, sometime there is a crack (eg from over vacuum sealing it) in the bag and you have to replace it. This situations I only had at the beginning when I had to getting used to it.

It is enough vacuum sealed when the bag has a little "bulge" (correct word???) into the "center hole" of the spool. Do not over vacuum sealing i! With a quick glance you see it the bag is still air tight or air came in. Using a container (with many other spools) you have to trust a humidity gauge you even don't know how precise it is - speaking of the parts you get for few bucks online...

I really don't see the advantage of a container/box (with many other spools) with an active de-humidifyer...it just consumes power. Yes, using a dryer is also consuming power and for sure more when drying at higher temperatures. But, you have to dry it anyway before you put it in a container/box.

Yes, I am also looking at the cereals boxes with such "for few bucks" humidity gauges and desiccant for which you can find many, many solutions online. One advantage of such a solution will be that you also can print out of such boxes. But at the moment I use vacuum bags...and it work (at least for me).

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

You are correct.  In my case, the cheap ones were not even bottoming out but were showing RH% that didn't make sense in a bag of desiccant and a couple of reference hygrometers.  They were off by over 10%. When the reference is reading 15% and the cheap one is over 25%, it isn't going to work as an indicator for dry filament.  Some of the cheap, inaccurate ones have been referenced by the "experts" to use.  My main indicators do bottom out at 10% and show "LO" when that is reached.  Of course, at 10%RH at 20 degrees, you shouldn't have any moisture issues with 99% of filaments.

Problem is that you don't know this unless you have something accurate to test against.  That is why I have a couple of DHT22's on order.  Have a HDC3022 on my wish list which is rated at 0.5%RH and 0.1 degree accuracy.  I can then compare my cheap sensors to an accurate reference.

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

Note, an electric dehumidifier (I got a small one for my home after the guitar complained in autumn) has an efficiency curve that drops significantly below 50 % RH and lower temperatures. Under tropical test conditions it'll collect buckets per day - per the advertised performance. But in an already fairly dry and cool (!) room don't be surprised to find only a few drops of collected water after hours or even none at all.

I originally planned to keep my MMU loaded permanently so the printer is always ready. But with 50 % RH I but moved away from that, unload it directly after printing or at the end of the day.

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

With mechanical hygrometers (synthetic hair), check the manual. They may need regeneration every six months or so by wrapping in a wet towel over night. Also, adjustment (calibration screw), if that procedure doesn't show 100 %. 

RE: Humidity Control For Filament Storage - How Tight Does a Container Have to Be?

In my experience, that is low enough for 99% of filament I use.

Posted by: @hyiger

Cheap hydrometers bottom out at 10% RH.