molecular sieve


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Old 12-12-21, 06:47 AM
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molecular sieve

On a previous post (dissicant type used in IGU panes? - DoItYourself.com Community Forums) Fritz1 and Pilot Dane spoke about the use of molecular sieve.
I am not familiar with this material, but it seems that I may be able to use it. Can I use this material for moisture control to keep ABS or PLA plastic filament dry?
These filaments tend to absorb moisture and causes them to become brittle and a poor conductor of heat to melt when in use. I'm currently using calcium chloride (along with low room humidity) as a desiccant of sorts. I can also use silica gel beads (they come in packet sizes). Although not ideal, I have use and a supply of the salt for other reasons. That is why I'm using it as a moisture control. It seems to work OK. But if the molecular sieve would work better and can be rejuvenated in an oven, that might be a better choice.
Any comment or suggestions? I'm not so much into this 3D printing that I want or need to buy a commercial dryer for this particular use. In fact, this 3D printer thing is just a small side thing I do occasionally (making lots of screen corners). The filament stays in storage most of the time. Just looking for alternatives and am curious about the molecular sieve thing.
 
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Old 12-12-21, 09:53 AM
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It's also a problem with stick welding rods. Many welders store them in a fridge or freezer to help protect against moisture. As you mentioned silica gel will work and is probably the most commonly available desiccant and is reasonably priced. Silica gel can also hold more water so you could go longer between recharges. Molecular sieve can work better at very high and low humidity and temperature but it can't store as much water.

 
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Old 12-12-21, 11:12 AM
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A key point is that any desiccant will eventually no longer be effective if it is exposed to atmosphere for a prolonged period of time, just like a sponge that is thrown into a pail of water. But like a sponge, it "can" be wrung out and reused if the moisture can be baked out of it. (Unfortunately that is not possible or practical with an IGU once it is installed). Like the welding rods that Pilot Dane mentioned, all desiccants must remain sealed in a low humidity environment to be effective... or go through a baking process as they are being sealed. (like an IGU) They all have a maximum absorbance limit that once exceeded, they no longer can absorb more.
 
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Old 12-12-21, 11:20 AM
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Thanks, guys, for the information.
 
 

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