Are we kidding ourselves about desiccant?  

RE: Are we kidding ourselves about desiccant?

Posted by: @hyiger

I found with plastic bags that over time they can get scratched or torn and will no longer be air-tight. I keep all of my hydroscopic filaments in Polymaker dry boxes with 2 desiccant chambers filled with activated alumina. For the nylon (PA), PC and TPU I'll put it in the dryer before a print even if stored in a dry box. 

How do you dry your activated Alumina?  I have been using the Polymaker boxes.  

RE: Are we kidding ourselves about desiccant?

Posted by: @cwbullet

 

Posted by: @hyiger

I found with plastic bags that over time they can get scratched or torn and will no longer be air-tight. I keep all of my hydroscopic filaments in Polymaker dry boxes with 2 desiccant chambers filled with activated alumina. For the nylon (PA), PC and TPU I'll put it in the dryer before a print even if stored in a dry box. 

How do you dry your activated Alumina?  I have been using the Polymaker boxes.  

When the box hydrometer reaches 25%, I dump it out on a baking sheet and put it in a convection oven at 250C for 2 hours. 

RE: Are we kidding ourselves about desiccant?

Thank you, 

RE: Are we kidding ourselves about desiccant?

Use dessicant that changes colour as it soaks up moisture. you will then know if it's working or not and when to refresh it.

RE: Are we kidding ourselves about desiccant?

Thanks.  I will find a decent convection oven at Goodwill.  

Posted by: @hyiger

 

Posted by: @cwbullet

 

Posted by: @hyiger

I found with plastic bags that over time they can get scratched or torn and will no longer be air-tight. I keep all of my hydroscopic filaments in Polymaker dry boxes with 2 desiccant chambers filled with activated alumina. For the nylon (PA), PC and TPU I'll put it in the dryer before a print even if stored in a dry box. 

How do you dry your activated Alumina?  I have been using the Polymaker boxes.  

When the box hydrometer reaches 25%, I dump it out on a baking sheet and put it in a convection oven at 250C for 2 hours. 

Use dessicant but still dry your filament before and after use and dry the dessicant at the same time.

Cheerio,

RE: Are we kidding ourselves about desiccant?

how do you dry filament if it's not in a dry box? I'm in Colorado so we don't have a lot of humidity around here.

RE: Are we kidding ourselves about desiccant?

Posted by: @dedepetro

how do you dry filament if it's not in a dry box? I'm in Colorado so we don't have a lot of humidity around here.

With a dedicated filament dryer like the Creality Space Pi (which is my favorite). 

RE: Are we kidding ourselves about desiccant?

Be careful of some colour changing desiccants.  Their indicators may not change until your filament has already absorbed too much moisture.  I bought a large bunch when I got into 3D printing but it didn't change colour until 40% RH at 22 degrees.  It started around 25%.  Much higher than I would store my filament at now.  

RE: Are we kidding ourselves about desiccant?

I live in Alberta and our humidity is similar.  What you have in your house will usually be higher and can be much higher than what is outside.  We still end up with high humidity days that can play havoc with your filament.  I use a food dehydrator.  It was cheap and for my filaments it works great.  Just doesn't go high enough for some filaments.  Second hand store in my area had some for less than $20.  

I am looking at a decent filament dryer, one where there is an actual air exchange.

RE: Are we kidding ourselves about desiccant?

Posted by: @robin_13

Be careful of some colour changing desiccants.  Their indicators may not change until your filament has already absorbed too much moisture.  I bought a large bunch when I got into 3D printing but it didn't change colour until 40% RH at 22 degrees.  It started around 25%.  Much higher than I would store my filament at now.  

You have to overdry the silica gel beads.  They turn color, but you need to let them dry a little further.  I have started using Alumina with blue color-changing beads for my engineering filaments.  I am going to try drying them in a convection oven.  

Posted by: @hyiger

 

Posted by: @dedepetro

how do you dry filament if it's not in a dry box? I'm in Colorado so we don't have a lot of humidity around here.

With a dedicated filament dryer like the Creality Space Pi (which is my favorite). 

I use the same kind.  I also have several polydriers.  I just received a new Sunlu E2 that was a return.  

RE:

Posted by: @robin_13

I live in Alberta and our humidity is similar.  What you have in your house will usually be higher and can be much higher than what is outside.  We still end up with high humidity days that can play havoc with your filament.  I use a food dehydrator.  It was cheap and for my filaments it works great.  Just doesn't go high enough for some filaments.  Second hand store in my area had some for less than $20.  

I am looking at a decent filament dryer, one where there is an actual air exchange.

Agreed. Dehydrators do work well on PLA and PETG.  Not so much on higher temp filaments.  

RE: Are we kidding ourselves about desiccant?

I finally put my hygrometer in the bag with my desiccant packages, which I had dried in a Blue-M convection oven. I expected them to still be quite dry, but they're sitting at 23% RH. Next, I'm going to fire up the kiln and dry some 4A molecular sieve. Bet that goes a lot lower!

RE: Are we kidding ourselves about desiccant?

Would you just put the filament you want to use in the dehydrater for an hour? Just before you want to use it? 

RE: Are we kidding ourselves about desiccant?

Posted by: @conrad-2

I finally put my hygrometer in the bag with my desiccant packages, which I had dried in a Blue-M convection oven. I expected them to still be quite dry, but they're sitting at 23% RH. Next, I'm going to fire up the kiln and dry some 4A molecular sieve. Bet that goes a lot lower!

I can’t wait to hear the results.

RE: Are we kidding ourselves about desiccant?

So, this morning I took my 4A molecular sieve out of the kiln and bagged it. I had aimed for a 500 F bake but it actually saw about 600 F at the peak. By number of hours and delayed handling, I probably didn't get it nearly as dry as is possible. I moved my hygrometer to the bag and after not many minutes it dropped to 7% RH. Putting a different number to it, my previous 23% number is about 3.1 grams of water per cubic meter. 7% is about 1 gram per cubic meter. Next, I'll make up some smaller bags and try it with filament. Right now I believe filament makes a good desiccant to keep your silica gel dry, but maybe not the reverse! If you have to use silica gel, I could make a case that storing it with a quantity of dry molecular sieve would keep it in better condition than just sitting in a bag or can.

RE: Are we kidding ourselves about desiccant?

An hour later and we're down to 5%, less than 3/4 gram of water per cubic meter. Now, I don't know how good my sensor is down at that level. It's a Switchbot Bluetooth IP65 indoor/outdoor sensor from Amazon. They claim +/- 1.8% on humidity, but don't specify a range.

RE: Are we kidding ourselves about desiccant?

Silica gel is less efficient than alumina or molecular sieve for absorbing moisture but it has an unquestionable advantage, It can be regenerated fast and easily in a microwave oven. Two or three minutes with a setting of 600W is enough. Regenerating alumina takes considerably more time and electrical energy.

Of course if the silica gel balls come inside a fabric/paper sachet,they must be removed from there before putting them in the microwave or you’ll fry the paper. That’s why dedicated silica gel containers with screw-on lids are for. Plenty of designs in thingiverse/printables. I print mine from PC so they’ll withstand temperatures up to 100C. For regenerating the silica gel in the microwave I use an oven glass tray.

I dont trust at all the accuracy of ordinary hygrometers under values of 20%. It takes quite expensive instruments to measure correctly very low percentages of humidity. I mean not only standalone units that cost a few bucks each but also measuring devices built in a filament drier from Sunlu, Polymaker, Prusa or whatever.

RE: Are we kidding ourselves about desiccant?

As a metrology geek, I tend to trust nothing! I have various humidity measuring devices that all agree closely, including a chilled mirror device of my own design, but there are many pitfalls when you get to the signal digit numbers. 5% is a dewpoint of about -9 degrees F and I don't know if my chilled mirror can get down that low. What I can say is that as things dry out, the response seems to be linear, so I doubt the readings are way off. Fortunately, we're not so interested in the high humidity end. We have to subject our products to that where I work and the humidity sensors we use don't have a great lifetime under high temp and high humidity conditions. I'm still of the opinion that keeping a large amount of filament dry with a small amount of silica gel is a big ask.

RE: Are we kidding ourselves about desiccant?

@bad-raven-2

Any chance of a photo of a PETG or TPU print?