How to measure filament moisture

[ido_nl]

There is a lot of information on why moisture in filament is bad and how to store filament the correct way. But I couldnt find anything on how to measure the moisture levels in your filament. How do you know how wet your filament is?

Could you use something like a Moisture Meter (like in the added picture)?

[Garyg]

Hi

Since people with more filament knowledge than myself have not commented.

I’ll start.

Maybe someone who knows will chime in.

I store my filament in 5 gallon buckets with flower drying desiccant in an old nylon stocking.

I dry the desicant for 24 hours in my food dehydrator.

I put an inexpensive relative humidity gage inside the bucket.

After drying the desicant, I put my filament in the bucket and seal it up.

After about 4 weeks of storage, my relative humidity gage reads something slightly less than 15% humidity at about 70 degrees F.

This strategy appears to work for ABS, nGen, PLA.

My work area is kept at 50% relative humidity.

My mounted spool hangs in the open room for about 2 weeks at a time.

I’ve noticed that at the end of being open in 50% relative humidity that there appears to be more die swell,

but for my projects after 2 weeks hanging open, I put them back in the bucket.

I renew the desicant every 2 months or so.

…

BUT

For a material called PCTPE, things are quite different.

I have a sealed enclosure with spool mounted inside.

I dry the PCTPE spool in my dehydrator for about 2 hours

then, I dry my desicant for 24 hours and put it in the sealed enclosure.

My humidity meter after this process reads about 10% relative humidity or less.

I can print for about 1 week before the humidity increases to something slightly above 15%

Then I notice very much die swell when watching the extruder push some filament into the air.

I use very little PCTPE because what I usually build is made of ABS.

Nylons are fussy that way.

…

I’ve been looking for exactly the answer to the question you have posed.

I have never seen a straight forward answer.

In the end, It appears that If you are not having dimensional problems or bubbling of the filament

as it extrudes, don’t concern yourself too much.

…

I hope my rambling here helps you in some manner AND

I’m hoping that anyone with knowledge in this area will comment.

[jfield]

In injection molding, for a inexpensive method to check if there was moisture in the pellets, I would use a hotplate and glass slides. You heat up 2 slides (the kind used for microscopes) to the melting temp of the plastic, put some pellets, or in the case of filament, cut up pieces, and then put the 2nd slide on top and squish it down. If bubbles are seen, then this is moisture. I have not tried this with filament yet, but it should work.

[ido_nl]

hi, thanks for the reply, that sounds like a good way to answer the moisture question. It does sound like some hassle though

[ido_nl]

thank you for sharing your experience, it sounds like a good way of working and something I am going to adopt.

I already have a dehydrator in my wishlist. Already have a air tight container that is going to be my print spool holder. And I am going to order some storage bags (Mylar).

About measuring the moisture, I saw someone adding a moisture meter (different type to the one I posted earlier) in the storage bag together with the filament… perhaps this is an ok solution

[NTX9Design]

So I am not seeing anyone advocating for purchasing a moisture meter. Is running a quick test and listening for popping is the easiest method for those of us who have a 3d printer?

I purchased a used food dehydrator similar to the snackmaster in that the heat element is in the lid of the assembly. Instead of cutting up the trays, I put them away and substituted a 5 gallon paint bucket with some holes drilled near the bottom. Seems to work fine but it would be nice to have some direct means to test the filament for moisture.

[jfield]

A moisture analyzer can cost $3000 to $5000. What I used to do many years ago, for seeing if plastic pellets had moisture in them was: Heat up a hot plate to the melting temperature of the plastic. Put 2 glass microscope slides on the plate to preheat. Put some pellets on one of the slides, and put the other slide on top and gently press down and squash the pellets, letting them melt. Look for bubbles in the plastic which is from moisture. You could cut up the filament in to pellet sized pieces.
Although, by the time you do all this, it might be quicker to just run it through the 3d printer extruder!